Preheat oven to 350 degrees.

In a large bowl, whisk together the flour, baking powder and salt. Set aside.

In the bowl of a stand mixer, beat the butter and sugar together until fluffy. Add the egg whites, one at a time, fully incorporating after each addition. Add the egg and vanilla, mix to combine.

Alternate adding the flour mixture and champagne, starting and ending with the flour. Stir in the sour cream until well combined.

Add 1 to 2 drops of pink color gel until the desired color is achieved.

Line a cupcake pan with cupcake liners and fill each liner halfway with batter. Smooth the tops with a spatula.

Bake for approximately 20 to 23 minutes, or until a toothpick inserted into the center comes out clean.

Transfer to a wire rack to cool for 10 minutes, then transfer the cupcakes onto the rack to cool completely. Repeat with any remaining batter.

Add the butter and cream cheese to the bowl of a stand mixture fitted with a paddle attachment. Beat on medium speed until light and fluffy.

Slowly add the sugar to the cream cheese mixture beating until light and creamy. Stir in the vanilla.

Transfer the frosting to a piping bag and frost the cupcakes. Decorate with sprinkles, if desired.