Turn oven temperature down to 350°F. Line 12 regular-size cupcake cups with cupcake liners.
In the bowl of your stand mixer or in a large bowl if using a handheld electric mixer, whisk together flour, sugar, baking powder, and salt. Add butter, sour cream, eggs, and vanilla and beat on medium for 30 seconds to one minute until very smooth, scraping the sides and bottom of the bowl at least once halfway through.
Add about 1 heaping tablespoon of batter to the bottom of each of the cupcake cups. Place a mini pie in each of the cups and press down until it almost touches the bottom. Fill the cups with just enough batter to cover the top of the mini pies and smooth over. You will not use all of the cupcake batter.* Do not overfill! .
Bake for 15 to 18 minutes until cupcakes are set and the edges spring back when lightly pressed.
Cool completely before frosting.