Funfetti layer cake is a moist and tender white cake full of rainbow sprinkles and frosted with the most decadent white chocolate buttercream.
Why You'll Love this Funfetti Layer Cake
It has so many sprinkles! This is the best celebration cake because it's speckled with so many rainbow sprinkles. You can't help but be happy when looking at it.
It has the perfect texture and birthday cake flavor. The cake is so tender and moist and vanilla bean paste gives it the perfect vanilla flavor.
It's frosted with white chocolate buttercream. This stuff is decadent and tastes just like a white chocolate truffle. It's my absolute favorite frosting ever!
Ingredients for Funfetti Layer Cake
Butter- make sure it's softened
Granulated Sugar
Egg Whites- make sure they're room temperature
Vanilla- I always recommend using vanilla bean paste, and especially in this case. It really adds the best flavor to this cake
Buttermilk-keeps this cake extra moist, make sure it's room temperature
Sour Cream- I recommend full fat, make sure it's room temperature
All Purpose Flour
Baking Soda & Baking Powder
Salt
Rainbow Sprinkles- jimmies for the cake batter and nonpareils for decorating
White Chocolate- I recommend using high quality white chocolate, my absolute favorite to use is Lindt
Powdered Sugar
Step by Step Instructions
See recipe below for complete measurements and baking time.
STEP ONE: Cream butter sugar together.
STEP TWO: Mix in egg whites and vanilla.
STEP THREE: Add in buttermilk and sour cream and combine.
STEP FOUR: Whisk flour, baking soda, baking powder and salt together.
STEP FIVE: Add dry ingredients to the wet and combine. Mix in rainbow jimmies.
STEP SIX: Grease 3 6" cake pans with nonstick spray and divide the batter between them. Bake the cakes and then let them cool.
STEP SEVEN: Make the white chocolate buttercream by whipping butter and mixing in melted white chocolate. Mix in sifted powdered sugar.
Make sure you whip your butter until it is pale in color and really fluffy. 
See recipe below for complete measurements and baking time.
Assembling the Funfetti Layer Cake
For These Steps You'll Need
- a cake scrapper
- a rotating cake turntable
- a cake frosting spatula
- a sharp knife
- a piping bag fitted with a large decorative tip (I love Wilton's 1M tip)
- 4-5 plastic straws (optional)
GETTING PERFECTLY SIZED CAKE LAYERS
Once the cakes are completely cooled, begin to make each layer as similar in size as possible. Usually you will only have to cut the tops off of each cake layer. With a sharp knife, remove the tops from each cake layer until each are flat and can be stacked evenly. So, each layer should sit flat on each other without the cake leaning.
CREATING THE CRUMB LAYER:
Then place a dollop of white chocolate buttercream in the center of your cake turntable. Place the first cake layer over it. Then add a generous portion of white chocolate buttercream on top of the cake layer and even it out with your frosting spatula, turning the cake table as you go. Place the next cake layer over top and repeat the step. Then place the final layer over the top and place small dollops of white chocolate buttercream on the outsides and top of the cake. Even out the frosting as much as possible with your frosting spatula.
Then with your cake scraper, scrape the icing across the cake, turning the cake table as you go to make this as easy as possible. This layer of frosting should be very thin. This is called the "crumb layer" and will ensure that the cake’s final coating of frosting is smooth and free of crumbs. Consider putting a few plastic straws through the cake if it needs stability to stand up straight.
FINAL FROSTING LAYER
Once the crumb layer of frosting has been applied, place the cake in the fridge for at least 20 minutes to allow the frosting to firm up. Once the cake has chilled in the fridge, remove it and apply the final coating of frosting. Apply generous dollops of frosting on the sides and top of the cake and smooth them out with your cake frosting spatula. Then with your cake scraper even out the frosting, turning the cake table as you go, to give you an even coating of white chocolate buttercream. You may have to do this step twice to make sure the frosting is on thick enough.
Decorating the Cake
Place the remaining white chocolate buttercream in a piping bag fitted with a large decorative tip. Take your rainbow sprinkles, I used a mixture of jimmies and nonpareils, and press them on to the outside of the cake. I chose to keep the sprinkles just on the bottom of the cake but you could coat the entire outside if you wanted! Sprinkle more sprinkles on top of the cake. Go around the outside edges of the cake and pipe decorative swirls of white chocolate buttercream. Sprinkle more sprinkles on top and then serve!
FAQs
How do I store the cake? Store the cake in an airtight container for up to three days. You can also slice and wrap individual pieces and freeze them for up to two weeks.
Can I use another kind of sprinkles besides jimmies in the cake batter? Jimmies are the best option for the cake batter. All other sprinkles tend to melt into the batter and won't be as noticeable, or might give the cake an unwanted ugly hue. I recommend sticking with jimmies.
Can this be made with gluten free flour? I've only tested this recipe with regular flour, but if you try it let me know how it turns out!
Can I bake the cake in two 8" pans instead of three 6" pans? Yes you sure can. I've only tested this recipe with 6" pans however. Bake the cakes at 350 degrees and begin checking for doneness around 28 minutes. Add more time as needed.
Pro Tips
Use 6-inch parchment paper rounds on the bottom of your cake pans. This really helps the cakes not stick to the bottoms.
Use a food scale to weigh the batter and make sure it's evenly distributed between each cake pan. This will give you the most even layers after baking.
Make sure all your wet ingredients are room temperature. This will give you the best textured cake.
If you make this cake please leave a star rating! Tag me on Instagram @inbloombakery_ so I can see! Follow me on Pinterest for other dessert ideas!
Other Recipes to Try
📖 Recipe
Funfetti Layer Cake
Ingredients
For the Funfetti Cake
- ½ cup + 2 tablespoon unsalted butter, softened
- 1 ½ cups granulated white sugar
- 1 tablespoon vanilla bean paste
- 4 egg whites, at room temperature
- ¾ cup buttermilk, at room temperature
- ½ cup sour cream, at room temperature
- 2 ¼ cups all purpose flour
- 1 ½ teaspoon baking powder
- ¼ teaspoon baking soda
- ½ tsp salt
- ½ cup rainbow jimmies
For the White Chocolate Buttercream
- 2 cups unsalted butter, softened
- 8 oz. white chocolate, melted and slightly cooled
- 2 ½ cups powdered sugar, sifted
- ¼ cup rainbow jimmies for decorating
- ¼ cup rainbow nonpareils for decorating
Instructions
For the Funfetti Cake
- Preheat oven to 350 degrees. Spray 3 6" cake pans with non stick spray and place a parchment paper round in the bottom of each pan.
- In a large bowl cream the softened butter and granulated sugar together.
- Add in the egg whites and vanilla bean paste and mix until smooth, about 1 minutes.
- Add in the buttermilk and sour cream and combine.
- In a separate bowl whisk together the flour, baking powder, baking soda and salt.
- Add the dry ingredients to the wet ingredients and mix the batter is smooth.
- Mix in the rainbow jimmies.
- Divide the batter evenly between the cake pans.
- Bake the cakes for 32-36 minutes, or until a toothpick comes out clean from the centers with just a few moist crumbs.
- Let the cakes cool in their pans for 5 minutes, then transfer them to a cooling rack to completely cool.
For the White Chocolate Buttercream
- Add the softened butter to a large bowl and mix with an electric mixer until pale in color and fluffy, 5-10 minutes.
- Then add in the melted and slightly cooled white chocolate and mix until combined. You'll want to make sure the white chocolate is just about room temperature, but still completely melted. If it's too warm the butter will melt and if it's too cold it can cause clumps of chocolate to end up in the frosting.
- Add in the powdered sugar a little at a time and mix until it is all combined and the frosting is light and fluffy.
Assembling the Cake
- One the cakes are cooled fill each layer and frost the outside with white chocolate buttercream. Add sprinkles to the top and outside of the cake. See the blog post above for all the step by step instructions along with photos.
🎉🎂 this is the perfect birthday cake!
Could you recommend a brand for the Jimmies? i have tried a couple of brands but they bled in the batter. Thanks!
Hey Karen! I use Betty Crocker and I haven't had any issues yet! 🙂
Can we replace the sour cream with yoghurt ??
Hi Chanchal. I have not tested this recipe with yogurt so I can't say for sure how the cake would turn out.
Can I use cartoon egg whites ?
Hi Adela! I have not tried this recipe with carton egg whites so I can't say for sure if it'll work the same.
Hi Ginny!
First time making one of your cakes — should I get 2” depth cake pans or 3”? I know they’re 6” in diameter but not sure if depth matters!
Thanks!
Lisa
Hi Lisa! You can do either 2" or 3" deep pans! Mine are 2" deep but 3" would work fine as well 🙂