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funfetti birthday cake recipe
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Double Funfetti Birthday Cake

The most celebratory cake of all! A delicious sprinkle-studded funfetti cake with funfetti buttercream that's always perfect for anyone's birthday or celebration.
Prep Time 40 minutes
Cook Time 35 minutes
Servings 15 slices

Ingredients

Funfetti Cake (from my book, Anyone Can Cake)

  • 2 3/4 Cups (290g) sifted cake flour* DIY recipe in notes
  • 2 tsp (10g) baking powder
  • 1/2 tsp baking soda
  • 1 tsp salt
  • 3/4 Cup (170g) unsalted butter, room temperature
  • 1 1/2 Cups (300g) granulated sugar
  • 2 large eggs + 2 large egg whites, room temperature
  • 1 tsp almond extract
  • 2 tsp pure vanilla extract
  • 1/2 Cup (120g) sour cream, room temperature
  • 1 Cup (240ml) whole milk, room temperature
  • 1/3 Cup (60g) rainbow sprinkles**, coated in 2 tsp cake flour

Funfetti Buttercream

  • 2 Cups (452g) unsalted butter, room temperature
  • 7 Cups (840g) powdered sugar
  • 4 tsp pure vanilla extract
  • 4 Tbsp whole milk, room temperature
  • pinch of salt, or to taste
  • 1/3 Cup (67g) rainbow sprinkles**

Optional Fillings & Toppings

  • 1 batch chocolate ganache recipe link below
  • 6 sprinkle cake truffles recipe link below

Instructions

Make the Funfetti Cake

  • Preheat the oven to 350°F/177ºC. Prepare three 6-inch or two 8-inch cake pans by spraying the sides with a baking spray (Baker's Joy is my favorite) and fitting a wax or parchment paper circle to the bottom of the pan. Alternatively, you can grease and lightly flour the pans.
  • Add the sifted cake flour, baking powder, baking soda, and salt into a medium bowl and whisk to combine. Set aside. 
  • In the bowl of your stand mixer (a handheld mixer works fine too!), cream the butter on high for 2 minutes. Add in the sugar and continue to beat on medium-high until light and fluffy (another 2 minutes), scraping down the bowl and paddle as needed. With the mixer on low speed, add the eggs and egg whites one at a time. Add the vanilla extract, almond extract, and sour cream. Mix for one minute on high speed, scraping down the bowl and paddle once more. 
  • Turn the mixer off and add in the dry ingredients all at once. Mix on low speed until just combined, then slowly pour in the milk while continuing to mix on low until incorporated, about 1 minute. Scrape down the sides and bottom of the bowl and give it a few stirs to make sure there are no lumps. The batter will be slightly thick.
  • Gently fold the flour-coated rainbow sprinkles into the cake batter by hand, then divide evenly between the prepared cake pans and bake for 32-36 minutes, or until a toothpick inserted comes out clean. Let the cakes cool in the pan for five minutes before turning them out onto a wire rack for an additional few hours of cooling. Make sure they’re entirely room temperature before applying any frosting.

Make the Funfetti Buttercream

  • With a hand mixer or stand mixer fitted with the paddle attachment, cream the butter on high until creamy and light (almost white) in color, about 7 minutes.
  • Turn the mixer to low speed and add the powdered sugar a few cups at a time, scraping down the bowl and paddle after each addition and making sure each is fully incorporated before adding the next one.
  • Add the vanilla, milk, and salt and mix on low for another minute until fully incorporated and smooth. Reserve 1 1/2 Cups of frosting if you plan on doing any piping on top of the cake at this point. Fold in the rainbow sprinkles to the rest of the buttercream with a rubber spatula.

Make the Chocolate Ganache (Optional)

  • If you're planning on filling and dripping the cake with chocolate ganache (like the one pictured), make one batch of this chocolate ganache. You can half the recipe if you're only wanting to use it for the drip.

Assembly

  • Once the funfetti cakes are completely cooled, level them to your desired height. If you're planning on making the sprinkle cake truffles, reserve some of the cake scraps from the leveling process in a small bowl and make them according to this recipe.
  • Add a swipe of funfetti buttercream onto a cardboard cake circle and place the first cake layer on top. Fill and stack the cake with funfetti buttercream. If you want to add chocolate ganache between the layers like the cake pictured, make sure the ganache is room temperature or slightly below (peanut butter-ish consistency) and use the Soft Fillings method of filling and stacking from this blog post. Crumb coat the cake with funfetti buttercream, then place it in the refrigerator for at least 30 minutes to let the buttercream set firm.
  • To create the design pictured, frost a smooth buttercream finish onto the cake with funfetti buttercream and place it back into the refrigerator for an additional 20 minutes to chill the buttercream while you heat the chocolate ganache to perfect drip consistency. Drip the cake with the chocolate ganache and place it back into the refrigerator for 5 minutes to let it set.
  • If piping the top of the cake, color the reserved buttercream any color you'd like. I used one small drop of AmeriColor Deep Pink. Fit a piping bag with Wilton Tip 1M and pipe 6 swirls on top of the cake, spaced about 1 inch apart. Fill in each gap with a sprinkle cake truffle.

Notes

*DIY Cake Flour Recipe: To make your own cake flour, spoon and level one cup of all-purpose flour and remove 2 Tbsp. Add 2 Tbsp of cornstarch. Repeat per the amount of cake flour you need, then sift the flour and cornstarch mixture 4 times (don’t skip that step!). After sifting, spoon and level to re-measure the amount of cake flour you need. 
**Rainbow Sprinkles: the best kind of sprinkles to use in this cake and buttercream are the rod-shaped kind that don't bleed color. Look for "carnauba wax" and "confectioner's glaze" in the ingredients list. These are coating agents that will keep the sprinkles from bleeding color into your batter and frosting. My favorite rainbow sprinkles to use are Sprinkle Pop's Ultimate Unicorn Rainbow Jimmies. 
Make Ahead Tips:
  1. The funfetti cakes can be baked, cooled, wrapped in plastic wrap, and left out at room temperature up to two days ahead of decorating. Unfrosted cake layers can be wrapped tightly in plastic wrap and stored in the freezer for up to two months before thawing and frosting. 
  2. For best results, reserve adding the sprinkles to the funfetti buttercream until right before you’re ready to decorate with it. The buttercream (sans sprinkles) can be made ahead and stored in an airtight container in the refrigerator for up to two weeks. When you’re ready to use it, bring it back to room temperature and re-whip in your stand mixer to bring back to smooth buttercream consistency, then fold in the sprinkles.