Yellow Cupcakes with Milk Chocolate Frosting

This was a favorite yellow cupcake recipe a few years back. Since then Ive worked to perfect them. My updated yellow cupcakes recipe is extra moist soft and packed with buttery vanilla flavor. Using cake flour instead of allpurpose flour adding sour cream and skipping the fluffy egg whites are the secrets. I would love to know if you try either recipe!
Ingredients
2 large eggs room temperature and separated
2 and 14 cups 266g sifted allpurpose flour spooned leveled
2 and 12 teaspoons baking powder

12 teaspoon salt
34 cup 12 Tbsp 180g unsalted butter softened to room temperature
1 and 34 cups 350g granulated sugar
3 teaspoons pure vanilla extract
1 cup 240ml whole milk room temperature
chocolate buttercream and sprinkles for decoration
Instructions
Preheat oven to 350F 177C. Line a 12count muffin pan with cupcake liners. This recipe only makes 1618 cupcakes so youll have 46 cupcakes to bake in a 2nd batch.
With a handheld or stand mixer fitted with a whisk attachment beat 2 egg whites on high speed in a medium bowl until soft peaks form about 23 minutes. You want them very fluffy no liquid at the bottom of the bowl which makes for too much liquid in the batter. See photo at the bottom of this post for a visual. Set aside.
Whisk the flour baking powder and salt together in a medium bowl. Set aside.
Using a handheld or stand mixer fitted with a paddle attachment beat the butter on high speed until smooth and creamy about 1 minute. Add the sugar and beat on high speed for 23 minutes until creamed together fairly well. Scrape down the sides and up the bottom of the bowl with a rubber spatula as needed. Add two egg yolks and the vanilla. Beat on mediumhigh speed until combined. Scrape down the sides and up the bottom of the bowl with a rubber spatula as needed. With the mixer on low speed add the dry ingredients in three additions alternating with the whole milk beginning and ending with the dry ingredients and mixing each addition just until incorporated. Do not overmix. Fold whipped egg whites into cupcake batter. The batter will be smooth velvety and slightly thick.
Spoon batter into cupcake liners filling halfway full. Bake for 1821 minutes or until the tops of the cupcakes spring back when gently touched and a toothpick inserted in the center comes out clean. Mine usually take 21 minutes. Dont overbake. Allow to cool in the pan for 5 minutes then transfer to a rack to cool completely.
Prepare chocolate buttercream. Pipe or spread the frosting onto cooled cupcakes. Decorate with sprinkles.