Halloween Sprinkle Slime Cake

Halloween Sprinkle Slime Cake

Last year's 'Halloween Slime Cake' was a huge hit...

Last year’s ‘Halloween Slime Cake’ was a huge hit on the blog, but I felt like something was missing when I looked at the pictures...I wanted the flask to stand out more!

This year I had an idea- could I color the flask with sprinkles? I found that shortening on the inside of the flask made the sprinkles stick super easily – and we were off!

Again - definitely one of the easiest Halloween cakes I've decorated. I love teal, but I'm still torn on whether I like the teal drip or the OG green drip better...jury's out. Choose your favorite color! 😉 

Since I wanted the whole recipe super-easy to make, I doctored up a couple of boxed cake mixes for these cake layers too. Worked great! A scratch recipe is also linked in the FAQ section for all my cake purists. 😉

Recipe and links to everything I used are below! 


"You used boxed mixes in this recipe - can I use a scratch cake recipe instead?" 
  • Absolutely! You use my Favorite Vanilla Cake recipe - or even your own favorite white or vanilla cake recipe! Just add food coloring as described in the recipe card if you want colored cake layers. 
"Can I buy frosting instead?"
  • Definitely! I'd recommend chocolate store-bought frosting and add black gel color, though the shade of black may be a little lighter. 
    Store-bought frosting is generally  thinner than my recipe; add 2 Tablespoons of regular or black cocoa powder at a time until you reach a consistency that spreads and stays in place on the cake well. 

"Any tips if I've never added a drip to a cake before?"
  • Don't stress! It's easier than you probably think it is! 🙂 
  • My biggest tips - make sure you measure your chocolate and heavy cream carefully. Also, I recommend a test drip first! Don't pour the mixture over your whole cake until you're confident in the thickness. 
  • I loved this YouTube tutorial by Sugar&Sparrow when I was new to cake drips! 

(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!) 

Halloween Sprinkle Slime Cake

My most popular Halloween 'Slime' Cake - with a fun sprinkle twist that shows off the 'Science experiment flask' topper!
Prep Time25 minutes
Cook Time35 minutes
Decorating time20 minutes
Total Time1 hour 20 minutes
Course: Dessert
Cuisine: American
Keyword: Halloween Cake, Halloween cake, Halloween Slime cake, Halloween mad science cake, Halloween Sprinkle Slime Cake
Servings: 16 servings
Calories: 752kcal
Author: Sarah H



Cake layers

  • 2 white cake mixes
  • 1 cup unsalted butter (or 2 sticks, melted & cooled - use instead of oil)
  • 8 egg whites (no yolks-you can use egg whites from a carton to avoid wasting the yolks)
  • 2 cups buttermilk (room temperature - use instead of water)
  • 2 tablespoons clear vanilla extract
  • 3-4 drops each teal, pink, and orange gel food coloring (I used Americolor gels, and chose colors based on my sprinkle mix - feel free to change out the colors, or even leave them out!)

Black cocoa cream cheese buttercream

Cake Drip & decorations

  • 6 ounces White Candy Melts I used Wilton Bright White
  • 3 Tablespoons heavy whipping cream I used an incredibly thick Costco brand; you may need a bit less depending on the thickness of your cream
  • 2-3 drops teal gel food coloring Add last; after candy melts are melted with whipping cream!
  • 1 teaspoon Crisco / vegetable shortening (to coat the inside of the flask)
  • 3-4 Tablespoons Sprinkle mix of your choice (I used ‘Freak Show’ by FancySprinkles but there are tons of other mixes like this one available online!)


Cake layers

  • Preheat oven to 350°F. Line three 8-inch cake pans with parchment rounds, or grease with non-stick or baker’s floured cooking spray.
  • Mix together all wet ingredients (butter, egg whites, buttermilk, vanilla) in a large bowl with a mixer or wire whisk. Blend in cake mixes for 30 seconds until moistened, then beat for 2 minutes until well combined.
  • Divide evenly into 3 bowls and color one pink, one orange, and one teal. Transfer batter to prepared cake pans.
  • Bake for 35-37 minutes (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. Cool completely before frosting. Set in the fridge or freezer to accelerate the cooling process if desired.


  • Beat together softened cream cheese and butter; slowly add in powdered sugar alternating with cocoa powder and milk until frosting reaches desired consistency. Add vanilla, black gel color, and salt if needed and beat until well combined.


  • Once your cakes are cool, level them (if needed/desired). 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 frosting.
  • Add your next cake layer on top, and repeat the process with your remaining cake layers.
  • 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.
  • Once your crumb coat has set (this takes about 5-10 minutes in the fridge), add your final layer of frosting and smooth. I like to use an offset spatula and bench scraper for this part. Once your cake is covered, place it into the fridge or freezer to set the frosting. (This is a great time to make and color your ganache drip!)

Cake Drip & Decorations

  • Place heavy cream and candy melts in a microwave-safe bowl (don't add the color yet!) and microwave on 50% power in 30-second intervals until smooth, stirring in between. Once the mixture is completely melted and smooth, add in the gel color and mix until the color is even.
  • Once your ganache has cooled to a moderate temperature - it should be liquid but not hot so it doesn't melt your frosting - transfer it to a squeeze bottle or piping bag. You can use a spoon; it just won't give you quite as much control.
  • Slowly drizzle candy melt ganache around the upper edge of your cake, pausing every inch or so to let more fall in a drip down the side of the cake. Smooth any gaps or bumpy spots with a small offset spatula.
  • With a bit of paper towel and a skewer, chopstick, or straw (anything long/narrow enough to fit) spread crisco around to cover the inside of the flask. I added a Crisco layer, set the flask in the cooling oven for one minute to melt down a little bit, and then spread it again with the paper towel so it wouldn’t look white and hazy.
  • Shake a few teaspoons of sprinkles into the flask, and then shake the flask until the inside is covered. (Optional - you can also use a shortening-covered finger to add some sprinkles to your drips!) Place the flask on top of the cake, adding a few more sprinkles so they look like they're pouring out of the flask.
  • And you’re done! Cut in and enjoy!



(Please note nutrition information is an estimate, and may not be exactly accurate.) 


Serving: 1slice | Calories: 752kcal | Carbohydrates: 98g | Protein: 9g | Fat: 38g

Did you make this Halloween Sprinkle Slime Cake? 

Send me an email and let me know how it went – or make my day and find me on Pinterest or on Instagram and tag @IntensiveCakeUnit in your photo!

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