Make the Cupcakes:

1. Preheat your oven to 350°F (175°C) and line a cupcake pan with cupcake liners.
2. In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.
3. In a large bowl, cream together the butter and sugar using a hand mixer or stand mixer until light and fluffy (about 2–3 minutes).
4. Add the eggs, one at a time, mixing well after each addition. Then mix in the vanilla extract.
5. Alternate adding the dry ingredients and wet ingredients (champagne and milk) to the batter, starting and ending with the dry ingredients. Mix until just combined.
6. Fill cupcake liners about 2/3 full and bake for 18–22 minutes, or until a toothpick inserted in the center comes out clean.
7. Let the cupcakes cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.

Make the Frosting:

1. In a large bowl, beat the softened butter until creamy and smooth.
2. Gradually add powdered sugar, one cup at a time, mixing well after each addition.
3. Mix in the champagne, vanilla extract, and salt. Beat for 2–3 minutes until the frosting is fluffy and spreadable. Add more champagne if the frosting is too thick.

Assemble the Cupcakes:

1. Once the cupcakes are completely cool, use a piping bag fitted with your favorite tip to frost each cupcake with the champagne buttercream.
2. Garnish with sprinkles, edible glitter, or a small piece of gold leaf for an extra festive touch.