Preheat the oven to 350 degrees. Line two cupcake pans with cupcake liners.
In a large bowl, whisk together the flour, baking powder and salt. Set aside.
In a large bowl, use an electric hand mixer to beat the sugar and butter 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.
Fill each cupcake liner halfway with batter. Smooth the tops with a spatula. Bake for 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.
PREPARE THE FROSTING:
In large bowl, use an electric hand mixer to combine the cream cheese and butter. 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.