Frost a Cake with Smooth Buttercream (how-to + video)

"How do I frost a smooth cake with buttercream?" 

Once upon a time, my only answer to that question would've been "Idk. I'm pretty sure getting frosting super smooth involves witchcraft." 

It used to take me multiple attempts - and literal hours of time - to get frosting even semi-smooth on my cakes. I'd get super frustrated, and eventually have to just say - "well, that'll have to be good enough." 

But! That was before I had the right cake tools and enough knowledge to see what I could've been doing better. So I write this post to hopefully make that process easier for you! 

(Disclosure: As an Amazon associate I may earn from qualifying purchases, and my posts often contain affiliate links. If you click a link and make a purchase, I may receive a commission at no extra cost to you!) 

(If you're looking for the video, use the 'Jump to Video' button above to watch the video on-page - or here to watch 'Smooth cake frosting! Tutorial + Troubleshooting' on Youtube.) 

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UPDATING TO ADD!! 

Since writing this post - and recording the accompanying video - I've learned a GAME CHANGER cake frosting hack. Credit to 'CravingAlishasCupcakes' on Instagram - I still can't believe how much an acetate sheet and a metal cake ring can speed up this process! 

I made a quick tutorial video here - it's a YouTube short for now; I'm hoping to get a more in-depth tutorial done as I do more experimenting with using the cake ring. 

Here are two quick links to the acetate sheet and the metal cake ring I used in the above 'cake ring frosting hack' video! 

Cake ring - https://amzn.to/4e0hHZA

Acetate - (the sheet I used was cut from an 8-inch roll) - https://amzn.to/3ABqnHI

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Okay - back to the classic frosting method! 

I won't lie - I hesitated to write this post (and make the accompanying video) for two reasons.

One, there are 1000 posts - at least - and more videos on YouTube to show you this already. I’m definitely not the first to post on this, nor am I the most experienced.

Second, one tip that I am going to share I expect to get some flak for. As always, a percentage of the internet’s going to be mad. 

BUT. I’m writing this post (/video) because I struggled as I was learning to frost a smooth cake with buttercream. And - the tip that was the most helpful for me I didn’t find in the first few videos that I watched. It won’t be for everyone, and I’ll get to that below - but I’ll post it in hopes it’ll help someone struggling like I was! 

So let’s get into it! 

You’ve baked the cake, made the frosting - now
how the heck do you get it onto the cake crumb-less and smooth? 

I’ll cover the equipment you need and the five basic steps first - 

Each step has its own section below, and I have a few tips for each step to help the process go more easily.  

Then, at the bottom of the post - I’ll get into some troubleshooting. I'll cover all the things that have tripped me up as I've put cakes together, and how to prevent them- or fix them if they’ve already gone wrong.

(I’ll also try and get the sections time-marked and linked in the description box in the video!) 

Okay! On to the reason you came here in the first place! 

Quick run-through of the minimum tools you'll need! 

Tools you need to get smooth frosting - 

• Cardboard cake circle - or a completely flat plate 

• Cake turntable

• Cake scraper or pastry cutter

Tools that are technically optional but REALLY nice to have - 

• Cake leveler (you can use a serrated knife instead) 

• Offset spatula (you could use a regular spatula or a large spoon)

• Cake pans with straight sides (many cake pans have angled-out sides for ease of storage - but those layers tend to be harder to frost smoothly.) 

1. Level your cake layers (once they're completely cooled, ideally well-chilled) 

• One of the BEST tricks to get your cake smooth is to start with even, level cake layers. You’ll have a *rough* time smoothing frosting over a cake that’s not holding still because of domed or slanted layers. (Trust me; I’m the idiot that tried. It went poorly.)
• So! Once your cake layers are completely cooled (and ideally chilled),  Trim down the tops until they’re flat. Then they'll  stack evenly without wobbling or tipping.
• You can do this with a cake level or with a serrated knife. I'll be honest; I personally haven't had the best time leveling with a knife. (Some people swear by it so I know it can be done; I’m just garbage at it.) Unless I only have a tiny bit of trimming from the cake tops, I really prefer (cough::completely depend on::cough) my cake leveler. 
• CAN you get smooth frosting on layers that aren’t perfectly level? Sure. You CAN fill in that gap with frosting. But it’s going to take more time, more frosting, and it’s likely to cause you a lot more frustration. I found early on that if my cake layers looked uneven before I started frosting, they also tended to look uneven after frosting. 
• Also worth mentioning - cake pans. If you have pans with slanted edges (so the pans stack together for storage) you may have a bit more trouble frosting evenly. You can make them work, but I eventually got rid of my slanted edge pans and bought straight edge pans, and had a much easier time frosting my cakes after I did.

2. Stack your cake layers: 

• Now that you have your cake layers level, it’s time to stack them! If you’ve ever built a block tower, it’s really not more complicated than that. After adding frosting/filling on the top of your first layer, center the next one on top. Repeat the process with your remaining cake layers.
• As I add sequential layers to the cake, I like to either hold my bench scraper up to them or give the turntable a quick spin watching the cake edges to make sure that I have the layers centered and even. 
• Now - that said - the other thing that could mess you up here is your cake filling. I’ll get into this more in the troubleshooting section, but you want to make sure the FILLING stays INSIDE the cake and doesn’t get out into your frosting! 
• If you’re filling the cake with frosting - cool, no issue. If you’re new to frosting cakes this is definitely your easiest option. 
• If you’re filling the cake with something other than frosting though - like ganache or jam - you’ll want to pipe a ring or ‘dam’ of frosting around the outer edge of your cake layer, and put the filling in the center. Also bear in mind the filling needs to have a thick enough consistency or be in a thin enough layer to handle the weight of all the cake layers going on top of it without ‘squishing’ down and making your cake sides bulge! 

3. Crumb coat and chill: 

• Some will say you can skip this step - and they’re not wrong - but especially if you’re newer to getting smooth frosting on your cakes I really recommend adding a crumb coat. 
• Spread a thin coat of frosting over your entire cake - this keeps crumbs out of your next layer! Cakes often have some crumbs on their edges that come off into the frosting when you start to spread it on the cake. 
• I move some frosting into a separate bowl so I don’t accidentally mix crumbs into my main frosting bowl. 
• Your crumb coat doesn't have to be completely smooth - but the smoother it is, the easier smoothing your next layer of frosting will be.
  Crumb-coating is essentially a 'practice round' for getting smooth frosting on your cake - the spreading + smoothing motions are the same! 
  It also doesn’t matter if the cake looks covered in crumb-filled frosting when you’re done.  (Honestly, that’s the whole point.)
• Here's the start of the tip I expect might be controversial - at this point I put my cake in the freezer for at least 30 minutes. Usually longer; often closer to an hour. I don't want to even be able to make a dent with my finger in the side before I start frosting. This has been a MASSIVE help to me in the frosting process! A cold cake will firm up your frosting layer, and make it MUCH harder to accidentally scrape back down to your crumb coat as you smooth your frosting. 
• At a minimum, chill the cake for 10-15 minutes in the fridge until it’s firm to touch and not sticky. The crumbs are now trapped in that first layer, and you can frost without them getting in your way!
  Speak of the devil…

4. Finally -frost your cake! 

• Now it's finally time to start working on that outermost frosting layer!
• Start by spreading a layer of frosting over the top of the cake, and a bit over the top edge. This sets you up to get a smooth top, and enough icing on the top cake edge for a sharp edge. 
• Next - Pipe or spread your final layer of frosting onto your cake sides - you want this one thicker than your first crumb-coat layer. I usually shoot for about 1/4-inch or so (a little over a half centimeter). 
• You’ve got two options here - 1) spread and smooth, or 2) pipe and smooth. 
  • I prefer spreading just because I find it easier. I can’t explain to you why; I just do. But I'll cover both here! Doesn't hurt to give both a go to see which one you prefer.  
  • To pipe your final layer on, you’ll want your remaining frosting in a piping bag with a flat icing tip like Wilton’s #789. Start at the base and work your way up a layer at a time, making sure the last layer comes up over the top edge of the cake a bit (this will be important later). Or - 
  • To spread your final layer on, you’ll want an offset spatula. You'll see me use a small one in the video/photos, but a large one is much faster. (I used a large one until I did too many cakes in a short time period and injured a tendon in my thumb; now I use a small one because there’s less resistance.) 
• Okay! Finally, onto the part you probably came here for - 

5. Smooth the frosting - and get that smooth sharp edge at the top! 

• Okay! Now your final layer of frosting is on - and if you’re like me it’s nothing close to smooth. What now? 
• This is where the magic of the cake scraper / pastry cutter comes in! 
• Place your pastry cutter with the base flat on your cake board or turntable. This will help you keep it straight up and down so your cake sides are straight. 
• This is where a quick watch of the video will be especially helpful. Hold the scraper with an edge touching the frosting, at an angle close into the side of the cake. Rotate the turntable, holding the scraper as still as you can. The frosting you leave behind probably won't be perfectly smooth, but it'll be better! 
• Clean the excess frosting off of your cake scraper (I usually use the side of the mixing bowl for this) - and repeat! Work your way around the cake, scraping/smoothing as you go.
• After your first couple of passes, you'll probably notice some holes and gaps in your frosting. With some frosting on your offset spatula, fill the holes in. (Use too much rather than too little. It doesn't have to be pretty.) Now repeat the smoothing process with your cake scraper. Getting closer! 😉 

• Here's where my maybe-controversial tip comes back in.

• Maybe I'm just an over-zealous cake scraper. But I used to have SO MUCH TROUBLE  with accidentally scraping most of my frosting back off. I'd have thin spots in the frosting where I could  see the cake layers again. SO FRUSTRATING! Then I accidentally left a crumb-coated cake in the freezer longer than I meant to. And it was the easiest frosting job EVER. The frosting close to the cake was so firm because the cake was so cold, I couldn't accidentally scrape it back off! It was a game changer, and I've put my crumb-coated cakes in the freezer before frosting ever since. 
  • One caveat - if you live in an area where's it's warm + humid, that last tip may not work for you. I haven't lived in super super hot or always humid areas. So I haven't had a huge issue with my cakes 'sweating,' or developing condensation on the sides because of the temperature change. If you live in a humid area and still want to try it, you'll either have to deal with a bit of condensation on the outside of the cake - or plan to crank up your A/C and run a fan. FYI! 
• As you've been working around the cake, you've probably noticed a bit of a frosting 'crown,' or rough-looking edge poking a bit past the top of the cake. This is a good thing! This is what you'll use to create a clean, sharp edge at the top of the cake.
  (If you haven't seen that 'crown' start to form, you probably don't have quite enough frosting at the top of the cake. Add more frosting to that top edge, and make another few passes with your cake scraper.) 

5.5 - Shaping the top edge of the cake 

• Once you're happy with the look of the sides of the cake and you see a frosting 'lip' or 'crown' around the top of the cake, you're ready to shape the top edge. 
• (Take a deep breath; you're almost there! This can feel a little nerve-wracking the first couple times you try it, but it's also super satisfying 🙂 
  ALSO - it doesn't matter if this doesn't go perfectly on your first try! You can always add a bit of frosting and re-smooth the sides to re-create that lip, and try shaping the edge again.) 
• Gently use your offset spatula/scraper to pull a small section of frosting 'lip in toward the center of the cake. Clean your spatula/scraper off after each pass. 
  • (Most posts I've read recommend the offset spatula for this; I know a few others that like to just remove that 'lip' with a sharp hot knife. But to be honest I usually have the easiest time shaping the top edge with my bench scraper. I can line the bench scraper up with the top of the cake and make sure I'm keeping it straight and not taking off too much frosting.)
• Continue working your way around the cake, pulling that top edge in to create a clean, sharp edge at the top of your cake! 

6 - Practice makes...better! 

• If your first few tries at frosting a cake don't go the way you want, that's NORMAL!
  If it feels like it's taking a MILLION years to smooth your frosting, that's  ALSO NORMAL!
  (If you get frustrated and want to throw your cake out the window - again, still normal!!) 
• None of these techniques are exactly complicated, but they're not really intuitive either, and every new skill takes practice.  
• Even cake decorators who have been frosting cakes for years sometimes struggle with frosting, and (despite what Instagram would have you believe) getting smooth frosting on cakes doesn't happen instantly for anyone. But the more you'll practice the better - and faster - you'll get! 

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FAQs & Troubleshooting

Alllllright. All of that said - nothing goes to plan 100% of the time.

Sometimes you've checked all the boxes and followed all of the steps and you're STILL glaring at a lumpy, bumpy, freakin' wonky-looking cake on that turntable. Now what?? 

This is where I'll do my absolute best to help you with troubleshooting! I'll try to cover the questions and the 'weird issues' that have come up for me and the people I've talked to about cake frosting. If you have a question that isn't in my list below please send me an email and ask! Emails through my contact page go straight through my inbox. 🙂 

"*Why* are my cake sides bulging?" 

There are actually a few possible reasons for this. 

1) your buttercream isn't quite thick enough, or

2) your cake filling is too soft or the filling layer is too thick (and it's trying to squish out the sides of the cake), or 

3) the cake layers are a little uneven, and as they're settling, trapped air pockets are causing the bulges. 

In my experience 1 and 2 are the most common, but 3's definitely a possible culprit as well. 

Making sure your buttercream is a good medium consistency, your cake fillings aren't too soft or layered on too thickly, and leveling your cake layers and pressing each one down a bit as you add each layer will help the cake settle without bulging between the layers. 

Having said all that - I recognize it's of limited help if you have a cake in front of you right now with bulged-out sides. So if you need a fix for a bulging cake right now - 

• Disassembling the cake and putting it back together is an option, albeit time-consuming and a bit of a nuisance. 
• You could also try putting the cake in the freezer for 20 or so minutes - this will set the frosting and hopefully a bit of the filling more firmly. Then spread another layer of frosting over the top, and try smoothing again. That's a bit of a "hail Mary" fix, and the bulges may come back if the cake comes back to room temperature, but it's something to try if you don't have time for a complete disassembly / reassembly. 

"Why are my cake layers sliding around while I'm trying to frost this cake??" 

Again - there are a few possible reasons. 

• The most likely - again - is your frosting isn't quite thick enough. Thickening your frosting with some powdered sugar - or using a firm stable recipe like American or Cream cheese buttercream - will help. 
• Another possibility is your cake filling is too wet or slippery - this happens to me often when I fill cakes with jam or macerated fruit. A thicker 'dam' or rim of buttercream around the outside of the cake layers will help. 
• A third possibility is one or more of your cake layers might be a touch uneven - an uneven base layer can tend to cause the next layers to tilt and slide. Making sure your cake layers are level and even as you stack should help. 
• Another 'quick fix' involves the 'cake-in-the-freezer-for-at-least-30-minutes' tip that I mentioned above. You might get a bit of condensation or 'sweating' if you're in a humid area, but a more stable cake will probably be worth it. 

"Why are my cake layers crumbling when I frost them? / Why is the frosting 'pulling' when I'm smoothing it?"

I grouped these questions because often the answer is the same - your buttercream might be a little bit too thick. 

Some cake layers are my prone to crumbling than others - this is just a function of the recipe components and how cohesive or dense the cake structure is. 

Try thinning down your frosting a bit with some milk or heavy cream - and / or try chilling your cake layers for at least 20 minutes before continuing. Chilled cake layers always handle more easily and crumble less! 

"This stupid cake frosting isn't...FROSTING!!" I'M SO IRRITATED RIGHT NOW!" 

I get it. You've done all the things; it's not working, you're aggravated. My best advice for this situation? 

Take 10. Just. Walk. Away. 

There it is. 

If that stupid cake just ISN’T smoothing the way you want it to, stuff it in the fridge. Take 10 minutes - or 15, or 20 - and go do something else. It’ll be fine in the fridge; you’ll get time to clear your head, and you can come back to it with a clean(er) slate. When you come back, spread a thin layer of frosting over the cake, and try it again. This is embarrassing to admit, but I 100% did this with the cake that I made to photograph for this post. Things ALWAYS go better for me after I take a break! 

That covers everything I have to tell you - for now! 

Please send me an email if you have any questions or issues frosting your cakes - I'm always happy to help however I can! Thanks to 2020 I have WhatsApp and Zoom; happy to schedule a call to help you troubleshoot if you're having a recurrent problem. 🙂 

Have fun - stick with it, keep practicing, and happy decorating! You've got this! 

Some cake recipes you could practice with -