To make the cake, preheat oven to 350 degrees F (180 C). Grease and flour three 8” cake pans; set aside.

In a medium bowl, whisk together the flour, baking powder, and salt set aside.

In the bowl of a stand mixer fitted with the paddle attachment, beat butter for 1-2 minutes. Add sugar and beat on medium-high speed for 2-3 minutes more, until the mixture is pale and fluffy.

Reduce speed to medium-low and add eggs one at a time, followed by the vanilla. Beat until thoroughly combined, scraping down the sides of the bowl if needed.

With the mixer running on low speed, add a bit of the flour mixture, followed by half the champagne. Add a bit more flour, then the rest of the champagne, and finally the last of the flour. Blend just until evenly combined.

Divide batter evenly among prepared cake pans, and smooth the tops with a spatula. Bake for 22-28 minutes, until the tops are just lightly golden and a toothpick inserted into the cake comes out with moist crumbs. Cool in the cake pans for about 15 minutes, then turn the cakes out to cool directly on wire racks until they are room temperature.

To make the frosting, beat the butter for 1-2 minutes, until it is smooth. Add 3 cups of powdered sugar, followed by the champagne, followed by the remaining powdered sugar, mixing well after each addition. Add more champagne or powdered sugar, if needed, to adjust the consistency, then frost and garnish the cake as desired.