PREHEAT oven to 350℉. Place baking cup liners in 2 muffin tins (20 liners).
MIX together butter and sugar in a large bowl until fluffy, then add in eggs one at a time.
COMBINE flour, baking powder and salt in a separate bowl. Then, gradually add in to larger bowl.
STIR in 3/4 cup sparkling wine, slowly, until well combined.
POUR batter into baking cup liners until about 2/3 full.
BAKE about 20 minutes, or until toothpick comes out clean. Allow to cool.
MIX buttercream frosting with 1/4 cup sparkling wine.
FROST cupcakes and serve.