Homemade Funfetti Cake

Arrange oven rack to middle position and heat oven to 350°F (175°C). Grease three 8-inch cake pans and line each with parchment paper. Set aside.

In a medium bowl, whisk together flour, cornstarch, baking powder, salt, and baking soda.

In the bowl of a stand mixer fitted with the paddle attachment, combine sugar, butter, and oil. Turn the mixer to medium-high speed and beat until mixture is light and fluffy, about 4 minutes.

Reduce speed to medium and slowly add whole eggs, egg whites, vanilla flavor, and food coloring (if using). Use a rubber spatula to scrape sides and bottom of bowl, then return mixer to medium-high speed and mix until everything is well-incorporated, about 1 minute longer.

Add half of the flour mixture and mix on medium-low speed until evenly incorporated, about 20 seconds. Add half of the buttermilk and mix until homogenous, about 20 seconds. Repeat with remaining flour mixture and buttermilk.

Use a rubber spatula to scrape sides and bottom of bowl. Gently fold in sprinkles, using no more than 4 to 6 strokes so the colors don’t bleed into the batter.

Divide batter evenly among 3 prepared pans. Bake until tops are golden brown and a toothpick inserted into center of cake comes out clean, 26 to 30 minutes.

Let cakes cool in pans on wire rack for 15 minutes. Run butter knife along edges of pans, then turn cakes out onto rack, right side up, and let cool completely before frosting, about 2 hours.

Spread 1 cup of frosting evenly over 1 cooled cake round. Top with a second cake round.

Spread 1 cup of frosting evenly over the second cake and top with the third cake.

Spread the remaining 2½ cups of frosting over the top and sides of the 3-layer cake.

Add sprinkles around the top edge of the cake (or in the design of your choice). Slice and serve.