Preheat oven to 350 degrees. Line standard muffin tins with paper liners and set aside. Sift flour, baking powder, and salt together; set aside. In large bowl using electric mixer, beat together butter and sugar until light and fluffy. Add sifted dry ingredients alternately with the Prosecco; set aside.
In large bowl, beat egg whites until stiff peaks form. Fold ¹/3 of egg whites into batter; gently fold in remaining egg whites. Fill cupcake liners to ²/³ full.
Bake for approximately 20 minutes, remove from oven and set aside to cool. Makes about 20 regular or 40 mini cupcakes.
With electric mixer, beat together sugar and butter until light and fluffy. Add vanilla and Prosecco beating on medium speed until well blended.