Preheat your oven to 350°F (175°C) and line a cupcake tin with cupcake liners.
In a mixing bowl, cream together the softened butter and granulated sugar until light and fluffy.
Beat in the eggs one at a time, ensuring each is fully incorporated before adding the next.
Mix in the peach puree, peach nectar, champagne, and vanilla extract until combined.
In a separate bowl, whisk together the flour, baking powder, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Do not overmix.
Divide the batter evenly among the cupcake liners, filling each about two-thirds full.
Bake in the preheated oven for 18-20 minutes, or until a toothpick inserted into the center comes out clean. Allow to cool in the tin for 5 minutes before transferring to a wire rack to cool completely.
For the champagne buttercream, beat the softened butter in a mixing bowl until creamy.
Gradually add the powdered sugar and beat until smooth.
Mix in the champagne and vanilla extract until well combined and fluffy. Adjust the consistency with more powdered sugar if necessary.
Once the cupcakes are completely cooled, frost with the champagne buttercream using a piping bag or a spatula as desired.