Preheat the oven to 350°F and line a cupcake pan with 12 liners.
In a large bowl combine the flour, baking powder and salt. Set aside. In the bowl of a stand up mixer add the butter and sugar. Beat on medium high speed until the butter is light and fluffy, around 2 minutes. Add the eggs, egg whites and vanilla and beat until just combined. Do not overmix.
Take the dry mixture and alternate adding it to the mixer on low speed with the champagne. Mix until all the flour is combined.
Add the mixture to the cupcake liners ¾ full. Bake for 18-20 minutes until the tops of the cupcakes are golden brown and a toothpick can come out clean from the center. Transfer to a cooling rack and let them cool completely before frosting.