Whisk buttermilk, eggs, and butter together in a bowl. Mix flour, sugar, baking powder, and salt together in a separate bowl. Whisk flour mixture into buttermilk mixture until smooth. Set batter aside until bubbling, 10 to 15 minutes. Pour champagne into batter; stir gently.
Grease a non-stick skillet lightly and heat over medium-high heat. Pour 1/3 cup batter onto the skillet; cook until bubbles form and the edges are dry, 2 to 3 minutes. Flip and cook until browned on the other side, 1 to 2 minutes more. Repeat with remaining batter.