Step 1

For the cupcakes: Preheat oven to 350 degrees F. Sift all-purpose flour and cake flour into a mixing bowl. Add baking powder and salt and whisk dry mixture, 20 seconds, set aside.

Step 2

In the bowl of an electric stand mixer, fitted with the paddle attachment, whip together butter and granulated sugar until pale and fluffy (occasionally stop mixer and scrape down sides and bottom of bowl throughout entire mixing process).

Step 3

Mix in egg, then mix in egg whites one at a time, blending until combined after each addition. Mix in vanilla and almond extract.

Step 4

Working in three separate batches, beginning and ending with flour mixture, add 1/3 of the flour mixture, alternating with 1/2 of the milk and mixing just until combined after each addition. Using a rubber spatula, gently fold in sprinkles.

Step 5

Divide mixture among 12 paper lined muffin cups, filling each about 3/4 full (about 1/4 cup in each). Bake in preheated oven 17 - 19 minutes until toothpick inserted into center of cupcake comes out clean.

Step 6

Allow to cool in muffin tin several minutes, then transfer to a wire rack to cool. Cool completely, then pipe (I used the Wilton 2E tip) or spread vanilla buttercream frosting over cupcakes and sprinkle with rainbow nonpareils. Store in an airtight container.

Step 7

For the frosting: In the bowl of an electric stand mixer fitted with a paddle attachment, whip butter on medium high speed until nearly white and very fluffy, about 7 - 8 minutes, frequently scraping down the sides of the bowl.

Step 8

Add in powdered sugar, heavy cream and vanilla extract and mix on low speed until blended, then increase speed to medium and beat until very light and fluffy, about 5 - 6 minutes, frequently scraping down the sides of the bowl.