In a small saucepan, bring the champagne to a boil over medium-high heat. Once boiling, reduce to medium heat and allow to simmer until reduced down to 1/4 cup, about 7-10 minutes. Set aside to cool completely. You want it room temperature or cold.

In a large bowl using a handheld or stand mixer fitted with a whisk attachment, beat the butter on high speed until completely smooth and creamy, about 2-3 minutes. Add the confectioners’ sugar 1 cup at a time, beating on low at first then increasing to high speed. Once incorporated, add the next cup. Once creamy and combined, beat in 3 Tablespoons of the reduced champagne and the vanilla extract. Taste. Add the remaining reduced champagne if needed, then a pinch of salt if you’d like.

Frosting can be made 2 days in advance, covered, and stored in the refrigerator until ready to use.