Preheat oven to 350°F (177°C).

In a large mixing bowl, whisk together the egg whites, milk, and the cake flavor or vanilla extract.

In another large mixing bowl, whisk together the flour, sugar, baking powder, and salt.

Add the butter to the dry ingredients and mix on medium speed for 30 to 60 seconds.

While the mixer is still running, add the egg and milk mixture to the dry ingredients and butter a third at a time, 20 seconds at a time.

When fully incorporated, scrape down the sides of the mixing bowl, and mix again on high speed for 40 seconds to aerate the batter.

Fold 1/4 cup of the sprinkles into the cake batter and mix until fully incorporated.

Line a 12-count cupcake tray with 12 jumbo cupcake liners. Fill each line 2/3 high with cake batter.

Bake the cupcakes in the middle of the oven for 30 to 35 minutes or until the cupcakes are golden brown and a toothpick runs clean when probed into the middle of the cupcakes.

Brush a thin layer of simple syrup over the cake and allow the cake to cool completely before serving or frosting.

In a clean mixing bowl, blend together the butter, powdered sugar, and cake flavor or vanilla extract. Blend on high speed for 5 minutes or until the frosting is white in color and fluffy. If desired, add 2 or more drops of food coloring, and blend for another minute.

Allow the cupcakes to cool completely. You can place them in the freezer for 20 minutes if you're short on time.

Using a spatula or a piping bag with an open or star tip, ice each cupcake with the buttercream.

Top your cupcakes with your favorite sprinkles.