Preheat oven to 350°F (175°C) and line a cupcake pan with liners.
In a bowl, whisk together flour, baking powder, and salt.
In another bowl, beat butter and sugar until light and fluffy.
Add eggs one at a time, beating well after each addition. Mix in vanilla extract.
Combine champagne, orange juice, and orange zest in a small bowl.
Add dry ingredients to the butter mixture in three parts, alternating with the champagne mixture and buttermilk, beginning and ending with the dry ingredients.
Divide batter evenly among cupcake liners, filling each about ⅔ full.
Bake for 18 minutes or until a toothpick inserted into the center comes out clean.
Let cupcakes cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.