Funfetti birthday cake is a moist vanilla cake studded with rainbow sprinkles, so it looks like confetti, hence the name Funfetti! This foolproof funfetti birthday cake is a fun and festive cake that instantly transports you back to your childhood.
Preheat oven to 350℉. Begin by combining the all-purpose flour, salt, and boxed cake mix together. Sift the dry ingredients together to get rid of any lumps. (You can also use a whisk, that works just as well).
In a stand mixer, place the unsalted room temperature butter inside the bowl and by using the paddle mix the butter until smooth and creamy. Then add the sugar, mix again until light and fluffy. Scrape down the sides of the bowl with a rubber spatula.
Now add the oil from the cake mix recipe. Slowly add in all the eggs from the pound cake and the cake mix (it should be around 7-8 eggs total depending on the cake mix). Then add the vanilla extract.
Remember to scrape down the sides of the bowl every few eggs to make sure everything is getting incorporated. At this point, the batter will look broken and weird, and you are probably thinking something went wrong no that’s okay, I promise it will look better after the next step.
Now add the dry ingredients to the mixer, it will become thick but still creamy. Next, slowly add the water (or milk is fine too) from the cake mix. Your goal at this time is just to mix the two recipes together to create a combined batter. Once you don’t see any visible dry ingredients turn off the mixer and you are done! Finally, add the ½ cup of funfetti sprinkles to the creamy cake batter. Then scrape down the sides of the bowl including the bottom of the bowl. This batter is really forgiving and will be fine.
Then prepare the cake pans with cooking spray and parchment paper lining the bottom of the pan. Pour or scoop the batter evenly into the prepared pans.
Place pans into preheated oven and bake the cakes for 30-35 minutes. You may need more time depending on the size of the cake pan. Check the center of the cake with a toothpick, and once it comes out clean, then it’s done.
Let cool slightly and carefully flip the cake out onto a cooling rack to finish cooling. This will prevent the cake from drying out while it's cooling down. Once cool enough wrap the cakes in plastic wrap and place the cakes into the freezer to prepare for decorating. Freeze for 30 minutes to an hour for decorating the same day or freeze up to 2 weeks to decorate later.
In a stand mixer bowl, add the unsalted room temperature butter. Mix on medium-high until the butter is light in color and fluffy. Stop the mixer every few minutes to scrape down the sides of the bowl to make sure all the butter is well blended. This step can take up to 5 minutes and is essential to whipping air into the butter, so your buttercream is the creamy smooth texture we want.
Once the butter is light in color and fluffy, continue to mix on medium and add the vanilla extract and salt. Scrape down the sides of the bowl again before moving to the next step.
Then gradually add half of the sifted powdered sugar to the butter mixture. Next, add 1 ½ Tablespoon of the heavy cream. Scrape down the sides of the bowl and especially the center of the bowl to make sure all the powdered sugar is getting incorporated.
Finally, add the last half of the powdered sugar and mix on medium-high. Continue to mix and scrape down the sides of the bowl until you don't see any more powdered sugar. If the buttercream is a little stiff, then mix an additional ½ tablespoon of heavy cream. Continue to mix until you have a creamy and smooth buttercream. The vanilla buttercream is ready to use.
In a medium glass bowl, melt pink chocolate candy melts in the microwave. Heat for 30 seconds at a time until the chocolate candy melts have mostly melted.
Then mix in the warm water with a rubber spatula. Continue to mix until the chocolate and water are well combined and streak free. If there are chunks of chocolate, melt for 10 seconds at a time until the chocolate is fully melted or pour the chocolate into a fine mesh sifter to remove any chocolate lumps.
Pour the chocolate into a squeeze bottle for a comfortable grip for decorating. If chocolate drip becomes too cold and hardens then heat in the microwave for 5-10 seconds, shake or stir to make sure its all the same temperature. Don’t overheat or chocolate will separate, and you’ll have to remix.
Remove the chilled cakes from the freezer and carefully slice the top of any dome of the cakes off to make them level and flat. This makes the stacking process much more manageable.
Next is decorating, use an offset spatula for layering the buttercream in between each cake layer. Continue to a crumb coat, so the whole cake is covered then chill in the fridge for 20 minutes until the crumb coat has set.
Next, add a thicker layer of vanilla buttercream onto the cake for the final coat. This is where you make the edges smooth and pretty. Place the cake back in the fridge for another 20 minutes to firm up the frosting before adding the pink chocolate drip lines.
Now it’s time to make pink chocolate drip lines. Use the slightly warmed chocolate squeeze bottle and start at the top of the cake right at the edge. Then squeeze the chocolate, so it runs down the side of the cake. Use different pressure to create the variable in the drip lines down the cake. Pour the chocolate on the top of the cake, so it's fully covered. Use the offset spatula to smooth the chocolate out.
Finally, add swirls of vanilla buttercream on top and add funfetti sprinkles on top and the bottom edges of the cake! Now you have a beautiful funfetti cake that’s ready to celebrate birthdays for years to come!
A single batch of this cake recipe makes 3 cake layers for 8” or 9” round cakes. Or can make 4 cake layers for 6” round cakes.