Heat the champagne in a medium saucepan over medium heat. Simmer down until it is reduced to ¾ cup. (Measure it out to make sure it has reduced enough) Do NOT allow the champagne to boil. Once the champagne is reduced, remove from heat and cool in the refrigerator.
Cupcakes
Line the cupcake pan and preheat the oven to 350°F
In a medium bowl, whisk together the flour, baking soda and salt. Set aside.
In a large bowl, cream together the granulated sugar, butter, and oil. Use a mixer and mix for about three minutes. It will look light colored and fluffy.
Continue beating while adding vanilla extract. Add eggs, one at a time, and mix until just incorporated.
Remove from mixer and stir in champagne reduction and milk. Continue to stir until fully incorporated. The batter may curdle slightly but that's OK.
Stir in the dry ingredients until combined, but try not to overmix the batter as it will result in dense cupcakes.
Fill cupcake liners ¾ full, and bake for 14-16 minutes. Use a toothpick to check for doneness by inserting one into the center. If it comes out clean or with loose crumbs, then it is done.
Remove cupcakes from oven, and cool on a cooling rack. Allow cupcakes to cool completely before frosting.
Champagne Buttercream
Beat the butter with an electric mixer until smooth and creamy, about 1-2 minutes.
Slowly add the powdered sugar and continue to mix until thoroughly incorporated.
Add in the salt and champagne reduction and mix well.
To pipe onto cupcakes, place frosting to a piping bag fitted with your preferred tip, and pipe frosting on using a circular motion. Top with sprinkles as desired.
Notes
STORE/FREEZEStore the cupcakes in an airtight container in the refrigerator for up to 5 days. Best if served at room temperature.To Freeze Leftover Frosted Cupcakes: Place them on a baking sheet with space between them. Freeze until solid. Wrap them individually with plastic wrap and place them in a freezer-safe container and freeze them for up to 3 months.To Freeze Unfrosted Cupcakes: Prepare the cupcakes and frosting but do not frost the cupcakes. Freeze them in separate containers for up to 3 months.Thaw them in the refrigerator overnight. Frost and decorate if needed.