Rainbow Birthday Cake

As much as I love striped cakes....

I love striped cakes, but to be honest – sometimes getting super clean stripes with a cake comb is frustrating even for experienced cake decorators and hecka intimidating for beginners!

I was working from a picture a client provided that had semi-messy stripes, and I loved the look! I kind of used my cake layers as a guide for how thick to make the stripes, then piped on the rainbow frosting and smoothed it out! Easiest striped cake I’ve ever done, and I loved the look when I was done!

Recipes, instructions, and links to supplies available online are below!
Video’s embedded and on my Tangi profile (Google’s newest video platform!)
Feel free to email me with any questions, and enjoy!

(Disclosure: As a way to keep my kitchen stocked with butter, sugar, and flour I am a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for me to earn a commission by linking to Amazon.com and affiliated sites.
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!) 

Vanilla Cake Layers:
Note - this is a slightly-simplified layer cake recipe from ChelSweets.com - I highly recommend checking out her site if you haven't before; it's amazing!!
3 1/4 cup all-purpose flour
3 cup  granulated sugar
2 1/2 teaspoon baking powder
1 teaspoon  salt
1 cup unsalted butter (or 2 sticks) room temperature
2 teaspoons clear vanilla extract
5 eggs 
1 1/2 cups buttermilk, room temperature (or buttermilk powder with water is an option if you can’t find liquid buttermilk at your grocery store!)
1/8 cup (28 grams) vegetable oil 
Preheat oven to 350°F. Line four 7 inch pans (for taller layers) or three 8-inch cake pans with parchment rounds, and /or grease with non-stick or baker’s floured cooking spray. 
Mix together all dry ingredients (flour, baking powder, sugar, and salt) in a stand mixer with a paddle until fully combined. 
Mix chunks of room-temperature butter slowly into the dry mix, on a low speed. Continue to mix until no large chunks of butter remain, and the mix becomes crumbly. 
Pour in eggs and mix on low until just incorporated.  Mix in the buttermilk in two installments, on a low speed. Add in vanilla and oil, and mix at a low speed until fully incorporated. Scrape down the sides of the bowl with a spatula, then beat on medium speed for about 30 seconds. Stir in crushed oreos and rainbow jimmies – the I stirred as little as possible after this point, to keep the Oreo crumbs from turning my cake layers brown!
Divide batter evenly between the prepared cake pans (I find a kitchen scale helpful for this part). This guarantees your layers will bake to be the same height.
Bake for 35-37 minutes if using 8-inch pans, or 37-38 minutes for 7-inch cake pans (or until a toothpick comes out clean). Allow cake layers to cool for 10-15 minutes on a wire cooling rack before removing from pans – it helps to run an offset spatula or knife around the perimeter of the pan first. Cool completely before frosting. Set in the fridge or freezer to accelerate the cooling process if desired.

Once the layers have fully cooled, the caramelized bits can be trimmed from the sides / top of the cake using a serrated knife if desired. Be sure the layers are completely cooled or chilled before trimming. If you try to trim the layers while they’re still warm, they will likely crumble and/or break.

This is a great time to make your frosting!
Cream Cheese Buttercream Frosting:
8 oz (one package) cream cheese, softened
16 Tablespoons (two sticks) butter, softened
6-7 c powdered sugar
2-4 Tablespoons milk
1 T clear vanilla extract
1/4 t. salt (if using unsalted butter)
Americolor gel food color – all the colors I used are available in this set!!

Beat together softened cream cheese and butter; slowly add in powdered sugar alternating with milk until frosting reaches desired consistency. Add vanilla and salt if needed and beat until well combined.
Divide frosting into 6 parts and color them red, orange, yellow, green, blue, and purple. 

Additional Supplies/Equipment:
- 1 8- or 10 -inch cardboard cake circle (I prefer Wilton’s center-punched circles)
- Cake leveler, cake turntable, large offset spatula, and pastry cutter/bench scraper - not all 100% necessary but incredibly helpful! (Here’s a link to the cake turntable I use)
- 6 piping bags or ziplock bags – I own this set of reusable piping bags, but since I needed so many I used zip-lock bags for this cake. Just add your frosting and clip a corner!
- Cake topper of your choice – I used one from this set!

Once your cakes are cool, level them (if needed/desired), and cut each one in half horizontally – this can be done with a cake leveler or a large serrated knife and a ruler. Place a smear of frosting on your cake circle (to keep the cake from sliding while you decorate it) and center your first cake layer in the center of the circle. Spread the layer with red frosting. Center your next cake layer on top.
Repeat the process with your remaining cake layers, with orange, yellow, green, blue, then purple frosting on top.

Now you're ready to crumb-coat . If you're unfamiliar with crumb-coating, it's just what it sounds like – spreading a thin layer of frosting over the entire outside of the cake to keep crumbs out of your final layer. I usually do this with my large offset spatula.
Let your crumb coat set in the fridge (about 10 minutes), and transfer the remaining colored frostings to each of 6 piping or zip-lock bags. Use the piping bags to add your final layers of each colored frosting, and smooth with your bench scraper. I don’t recommend an offset spatula at this step; it’ll probably smear the colors too much. As you smooth, you may need to fill some holes with more frosting from your piping bags or with a small offset spatula – continue filling and smoothing until you’re happy with the frosting!

Use the bench scraper to pull in the edges and smooth the top of the cake – add the cake topper and you’re done! Congratulations!

Make this recipe? Let me know how it went - or find me on Pinterest or on Instagram and tag @IntensiveCakeUnit in your photo!

Leave a Comment

Your email address will not be published. Required fields are marked *