1 cup all-purpose flour
1/2 teaspoon baking powder
1/4 teaspoon salt
1/2 cup natural peanut butter
6 tablespoons unsalted butter, room temperature
1/2 cup packed light-brown sugar
1 large egg, plus 1 large egg yolk
1/4 cup buttermilk
1/4 teaspoon vanilla extract
48 miniature Reese's peanut butter cups
48 pieces candy corn, for decorating
Preheat oven to 350 degrees. Line a 24-cup mini muffin pan with paper liners. In a medium bowl, using an electric mixer, beat together peanut butter, butter, and brown sugar on high until pale and fluffy, about 3 minutes. Beat in egg and egg yolk, scraping down bowl as needed. With mixer on low, beat in flour mixture, buttermilk, and vanilla until combined.
With the large end of a melon baller, place 2 teaspoons batter into each muffin cup.
Press a peanut butter cup into each center until batter aligns with top edge of candy.
Bake until puffed and set, 10 minutes.
Immediately place a piece of candy corn on top of each cupcake; let cool completely in pan on wire rack.
Repeat with remaining batter and candy.