Preheat oven to 350 degrees. Line a cupcake tin with cupcake liners.

In a bowl, whisk together flour, baking powder, baking soda and salt.

In a large mixer bowl, combine butter, sugar and orange zest. Beat on medium speed for 2 to 3 minutes, until light and fluffy. Add vanilla and orange juice, then add eggs one at a time, mixing well after each addition.

In a separate bowl, whisk together sour cream and champagne.

Alternate adding flour mixture and champagne mixture to butter mixture in 2 rounds, mixing just until batter comes together.

Divide batter between cupcake tins, filling them about ¾ of the way full. Bake for 18 to 20 minutes, until a toothpick inserted into the center of a cupcake comes out clean. Let cool completely before frosting.

Make the frosting: While cupcakes are baking, add champagne to a small saucepan over medium-high heat. Bring to a boil, then reduce to medium and let simmer for about 7 to 10 minutes, until mixture is reduced to 3 tablespoons. Remove from heat and let cool completely. (You may refrigerate it to speed this up.)

In a large mixer bowl, beat butter on high for about 2 to 3 minutes until light and fluffy. Add powdered sugar in 3 additions, beating between each addition.

Add 2 tablespoons of the reduced champagne, vanilla extract and orange zest, and continue beating until smooth and creamy. If needed, add remaining 1 tablespoon of champagne.

Frost the cupcakes, then garnish with an orange wedge.