Preheat oven to 350F degrees. Line a cupcake pan with paper liners.
In a large bowl, beat together the sugar and butter until the mixture is light and fluffy. About 2-3 minutes.
Mix in the vanilla extract and egg whites until well combined.
In a smaller bowl, using a fork, mix together the flour, baking powder and salt.
Add the dry mixture into the wet mixture and mix until well combined. Slowly pour in the champagne and continue mixing until the batter is smooth and free of lumps.
Fill the 12 cupcake liners evenly with the batter. Bake for 20-23 minutes, until a toothpick can be inserted and come out clean. Cool completely (about 2 hours) before frosting.
For the frosting:
In a large bowl, using a hand or stand mixer, cream together the butter and powdered sugar until a thick creamy consistency has been reached. This may take a few minutes.
Add in the vanilla and champagne and mix together until smooth and creamy. This will make a very creamy frosting and is perfect for spreading or piping.
If the frosting is a little too soft, add a little more powdered sugar to thicken. If the frosting is too thick, add a little more champagne to thin it out.
Fill a piping bag and decorate the cupcakes as desired.
Store covered in the refrigerator for up to 5 days.
Notes
This cupcake has a semi dense consistency, similar to a wedding cake. For a lighter, fluffier cupcake, try using cake flour instead of all-purpose flour.
I decorated these cupcakes with pearl candy and rose gold straws. You can usually find these at any craft store these days or even order them online if you prefer.
For the frosting, I used a Wilton 1m closed star piping tip.
I baked the cupcakes in a regular white paper liner. After they were done baking, I popped them straight into a decorated liner. It is not necessary, I just like how much more festive it makes them look!