Orange and Chocolate Mini Cupcakes with Butter Cream Frosting

Why I Love This Recipe
I use a generic base for cupcakes and add my flavors from there... this one is for the Orange and Cocoa flavors.
Ingredients You'll Need
Cupcakes:
1/2 cup milk
3 large egg whites(do not discard yolks, you'll need them for frosting)
1 1/2 tsp vanilla extract
Zest of 1 fresh orange (or 1 Tbsp dried zest)
1 1/4 cups all purpose flour
1/2 cup cocoa powder unsweetened
1 cup sugar
1/4 tsp kosher salt
2 tsp baking powder
6 tbsp softened butter
Butter Cream Frosting:
1/4 cup softened butter
3/4 cup powdered sugar
1/2 tsp vanilla (or orange extract for more citrus flavor)
1 egg yolk
a few drops of food color, whatever you want
Directions
Preheat oven 350
Mix milk, egg whites, zest and extract set aside.
Mix flour, sugar, cocoa, baking powder and salt. Add butter while mixing on low one tbsp at a time. Mixture should be crumbly looking.
Add milk mixture slowly and mix on low for a minute and a half until mousse like.
Pour into cupcake/muffin tins with liners. Bake 18-22 minutes. (Until toothpick comes out clean.)
While cupcakes cool mix together all frosting ingredients until whipped nicely. Put on cupcakes when completely cool and serve.