Champagne Cupcakes with Champagne Buttercream

I found this recipe and others buried in my email inbox, so I figured I'd share!  

Cupcakes:

2 3/4 cup all purpose flour
3 tsp baking powder
1 tsp salt
2/3 cup unsalted butter, at room temperature
1　3/4 cups sugar
3/4 cup champagne
1/2 tsp vanilla extract
6 egg whites

Preheat oven to 350 degrees and line muffin pan with paper liners (recipe yields about 22 cupcakes).　

Combine flour, baking powder and salt in a large bowl and whisk to combine. In mixing bowl, cream butter and sugar on medium high speed until light and fluffy, about three minutes. Add flour mixture in three additions, alternating with two additions of champagne combined with vanilla.　

In a clean bowl, beat egg whites on high speed until they hold stiff peaks. Fold in about 1/3 of the egg whites to lighten the batter then gently fold in the remaining egg whites. Transfer batter to cupcake liners, filling each about 2/3 of the way full. Bake approximately twenty minutes, until a toothpick inserted in the center comes out clean. Cool about five minutes in the pan and then transfer to a wire rack to cool completely.

Frosting:

1 cup unsalted butter, at room temperature
1/2 tsp vanilla extract
3-4 cups powdered sugar
3 T champagne

In a large mixing bowl, beat butter on medium high speed until smooth and fluffy, about three minutes. Add vanilla extract and about three cups of powdered sugar. Mix on low speed to combine.　 Add in champagne and mix on low to incorporate. Increase speed to medium and beat about one minute to whip frosting. If frosting appears to be thin, add additional powdered sugar as necessary to reach desired consistency