Preheat your oven to 177 degrees Celsius (350 degrees Fahrenheit). Grease two 9-inch round cake pans with butter or nonstick spray. Line the bottom of each pan with a circle of parchment paper and grease the parchment.

Set out butter, eggs, milk, and sour cream to reach room temperature.

In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.

In a large mixing bowl, beat butter and sugar together until light and fluffy, about 4 to 5 minutes.

Add egg whites one at a time, beating well after each addition. Then add vanilla and almond extracts.

Alternate adding the flour mixture and a combined milk-sour cream mixture to the butter mixture, starting with flour and ending with flour. Mix on low speed.

Gently fold in the rainbow sprinkles with a rubber spatula.

Divide batter evenly between prepared pans and smooth the tops. Bake for 28 to 32 minutes, until a toothpick comes out clean.

Cool in pans for 15 minutes before flipping out onto a wire rack. Let cool completely for at least 1 hour before frosting.

Beat softened butter in a bowl until light and smooth. Gradually add sifted cocoa and powdered sugar, mixing on low speed.

Add heavy cream, vanilla, and salt. Beat until fluffy and smooth.

Place one cooled cake layer on a plate, spreading frosting on top. Add the second layer and apply a crumb coat of frosting around the cake.

Refrigerate for 20 minutes, then add a final coat of frosting and decorate with additional sprinkles.