Preheat oven to 350° F and line cupcake tin with liners.
In a large bowl, with electric mixer, or in stand mixer, cream together butter and sugar until fluffy. Add vanilla extract and eggs, mixing in between each addition and scraping down sides of bowl as necessary.
Stir in the champagne.
In a separate bowl, whisk together flour, baking powder, and salt. Add dry ingredients to wet ingredients and mix to fully combine. Make sure you don't over-mix.
Scoop batter out into prepared cupcake liners, filling 2/3 full. Bake at 350° F for 18-20 minutes or until toothpick inserted in center comes out clean.
Remove from oven and let cool for 5 minutes in pan and then transfer to wire rack to cool completly.
While cupcake are cooling, make frosting by creaming together butter and vanilla until fluffy. Add champagne and mix. Add powdered sugar 1 cup at a time and whip until peaks form.
Scoop out into piping bag and pipe onto cooled cupcakes.