Preheat the oven to 350°F. Line three 9-inch round cake pans with round parchment paper liners. Spray the cake pans with baker’s spray (Baker’s Joy or a generic version).

Add the flour, baking powder, baking soda, and salt to a medium-sized mixing bowl (2-3 quarts). Whisk to combine.

Using a stand mixer or a large mixing bowl (4-6 quarts) and a handheld mixer on medium-high speed, beat the butter for about 1 minute until smooth. Add the vegetable oil and continue to mix for another 1-1½ minutes until smooth and completely incorporated.

Add the sugar, vanilla, and almond extract. Continue mixing for 1½-2 minutes until the mixture is combined and smooth.

Lower the mixer speed to medium-low. Add the eggs and egg whites, one at a time, until no yellow streaks remain and no streaks of the egg whites are visible.

Add the flour mixture 1½ cups at a time, alternating with the buttermilk, mixing well after each addition just until well incorporated.

Fold in the rainbow sprinkles.

Divide the batter evenly between the 3 prepared cake pans. This measures out to about 3-3¼ cups per pan. Bake for 30-35 minutes, or until a toothpick inserted comes away clean. Allow the cakes to cool completely while you prepare the frosting.

Using either a stand mixer or a large mixing bowl and a handheld mixer on medium-high speed, beat the softened butter for 1½-2 minutes or until smooth. Add the clear vanilla flavoring and almond extract. Mix just until incorporated.

Add the powdered sugar 2 cups at a time, alternating with the heavy cream, beating well after each addition until smooth. Be sure to scrape down the sides of the bowl. Measure out a generous ½ cup of frosting to pipe the rosettes (this is optional).

Once the cakes have completely cooled, remove the first cake from the pan. Peel the parchment paper circle from the bottom of the cake. Place the first layer on a serving plate or a disposable cake circle.

Add 1½ cups of the frosting to the top of the cake. Use an offset spatula to smooth the frosting over the top of the cake. Repeat the steps for the remaining layers. For the top layer, you can add a bit of a thicker layer of frosting.

Smooth the remaining frosting over the sides of the cake. If there are quite few cake crumbs, you can spread a very thin layer of frosting around the sides of the cake and then chill the cake in the refrigerator for 10-15 minutes. This is called a crumb coat. This will firm up the thin layer of frosting. You can then have a firmer base to spread the remaining frosting.

Add the rainbow sprinkles to the bottom half of the cake.

Add the reserved frosting to a disposable piping bag fitted with a star-shaped decorator's tip (I used Wilton 1M). Using even steady pressure, hold the tip ½ inch above the surface edge of the cake to form the rosettes. Sprinkle with the rainbow sprinkles once all rosettes are made. Slice and serve.