for the cupcakes
1 cups boiling water
1/2 cup unsweetened cocoa powder
1 1/2 cups all-purpose flour
1 teaspoons baking soda
1/2 teaspoon baking powder
1/2 teaspoon salt
1/2 cup butter, softened
1 cup granulated sugar
1 teaspoon vanilla extract
24 mini-Reese’s peanut butter cups
for the frosting
1 cup confectioners’ sugar
1 cup creamy peanut butter
5 tablespoons unsalted butter, at room temperature
3/4 teaspoon vanilla extract
1/4 teaspoon kosher salt
1/3 cup heavy cream
additional mini-Reese’s peanut butter cups
For the cupcakes: Preheat oven to 350F. Line a standard muffin pan with paper baking cups, and set in your batter dividers and set aside.
In medium bowl, pour boiling water over cocoa, and whisk until smooth. Let mixture cool. Sift together flour, baking soda, baking powder and salt; set aside. In the bowl of a stand mixer, cream butter and sugar together until light and fluffy. Beat in eggs one at time, then stir in vanilla. Add the flour mixture alternately with the cocoa mixture, ending with the flour.
Fill the lined muffin cups three-quarters full, being careful not to overfill. Insert a mini-peanut butter cup into the center of each cupcake and cover with batter with a small spoon. Bake until a toothpick inserted in the center of the cupcake comes out clean, about 18 to 20 minutes. Cool the cupcakes in the pan for 5 minutes, then transfer to a wire rack to cool completely.
To make the frosting, place the confectioners’ sugar, peanut butter, butter, vanilla and salt in the bowl of an electric mixer fitted with a paddle attachment. Mix on medium-low speed until creamy, scraping down the bowl with a rubber spatula as you work. Add the cream and beat on high speed until the mixture is light and smooth.
Pipe frosting onto cooled cupcakes and decorate with mini-Reese’s peanut butter cups.