Preheat oven to 350 F. Line a muffin pan with cupcake liners.

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

In a large bowl, beat sugar and butter together on medium speed until light and fluffy.

Reduce to low speed and add the egg and egg white to the butter mixture one at a time. Beat well after each, and add in vanilla.

Add the flour mixture to the butter mixture in three additions, alternating with the champagne in two additions. Beat until just combined, being careful not to over beat.

Divide the batter evenly into the prepared muffin pan, filling each about ¾ of the way full.

Bake for 18-20 minutes or until a toothpick inserted in the center comes out clean.

While the cupcakes bake, start the champagne reduction for the frosting. In a small saucepan, bring the 1-cup of champagne to a boil over medium-high heat. Once it’s reached a boil, reduce the heat to medium and allow to simmer until reduced to about ¼ cup (8-10 minutes). Once reduced, reserve 2-3 tablespoons for the frosting and use the rest to brush the tops of the warm cupcakes.

Let cupcakes cool completely on a wire rack.

In a large bowl, beat butter, sugar, vanilla, and 2 tablespoons of the champagne reduction together until smooth.

Taste and add additional champagne reduction if needed.

Transfer frosting to a piping bag with a star tip and frost cupcakes.

Once frosted, cupcakes can be placed in the fridge to help the icing set.

Place a piece of wax paper onto the counter or onto a baking sheet.

Place candy melts in a microwave safe bowl. Melt in the microwave, stirring every 30 seconds.

Transfer to piping bag and cut a small amount of the tip off. Pipe fireworks design onto the wax paper. Make sure to add a stem to the bottom of the design that will stick into the cupcake.

While the candy melts are still wet, sprinkle sanding sugar on top of them.

Once the candy has set, shake off the excess sanding sugar and stick into the frosted cupcakes. If your cupcakes have been in the fridge, use a small spoon handle or a knife to press a small hole into the frosting for the candy firework to go into.