Preheat your oven to 350°F and place a liner in each well of a cupcake pan.
In a medium bowl, combine the flour, baking soda, baking powder, and salt. Set this aside for now.
In the bowl of a stand mixer fitted with the paddle attachment, beat the granulated sugar, butter, and oil on medium-high speed for 1½-2 minutes, or until light and fluffy. Then, add the vanilla, egg, two egg whites, Greek yogurt, and continue beating until smooth.
Turn your mixer to low speed. Add half of the flour mixture, then the champagne, and then the remaining flour. Once you have added the last of the flour, turn the mixer off and use a flexible rubber spatula to fold the remaining flour in until it is just combined. Do not overmix the batter.
Divide the batter between the cupcake tins. This should make 12 cupcakes. Bake for 19-21 minutes, or until the tops are set and spring back when you tap them. Let the cupcakes cool for 5 minutes in the pan before transferring them to a wire rack to cool completely.
Make the frosting. Once again in a stand mixer fitted with the paddle attachment, beat the butter and salt together until smooth and combined. Then add the remaining ingredients and continue beating on medium-high speed until the frosting is light and fluffy.
Frost the cupcakes with a knife or piping bag and enjoy with a big glass of bubbly! :)