Let butter and eggs stand at room temperature for 30 minutes. Meanwhile, line cupcake pan with paper cups (or grease and flour silicone baking cups). In small Mixing Bowl, stir together flour, baking powder, baking soda, and salt. Set aside.
Preheat oven to 350 degrees Fahrenheit. In a large mixing bowl, beat butter with an electric mixer on medium to high speed for 30 seconds. Gradually add sugar ½ cup at a time, beating on medium speed until light and fluffy. Add eggs one at a time, beating after each addition. Beat in melted chocolate and vanilla extract. Alternate adding flour mixture and water to butter mixture, beating on low speed after each addition until combined.
Spoon batter into prepared baking cups, filling each cup half to two-thirds full. Use the back of a spoon to smooth out batter.
Bake 18 to 22 minutes or until a toothpick inserted in centers comes out clean. Cool cupcakes on wire rack.
Using a small spoon or an apple corer, scoop out about 1 inch from the center of each cupcake, leaving a ½-inch rim around the edge. Spoon or pipe 1 tablespoon of prepared Peanut Butter Filling (see instructions below) into the center of each cupcake. Cover and chill until serving time.
Just before serving, pipe Chocolate Butter Cream Frosting (see instructions below) over the top of each cupcake. Dust cupcakes with powdered sugar.
Peanut Butter Filling
In a mixing bowl, beat peanut butter and powdered sugar with an electric mixer on medium speed until smooth. Gradually add water (we added approximately 4 tablespoons) while mixing until it reaches a smooth consistency that sticks to the back of a spoon when turned upside down. Set aside or place inside a plastic pastry bag.
Chocolate Butter Cream Frosting
Allow butter to stand at room temperature for 30 minutes. Sift together powdered sugar and cocoa powder. Set aside.
In the mixing bowl, beat butter with electric mixer on medium speed until smooth. Gradually add 1 cup of powdered sugar/cocoa powder mixture and unsweetened chocolate beating well. Beat in milk and vanilla. Slowly beat in additional sugar/cocoa powder mixture. Beat in up to 1/4 cup additional milk until frosting reaches a piping or spreading consistency.
Spoon into a large plastic pastry bag fitted with star tip.
Last Step! Please leave a review and rating letting us know how you liked this recipe! This helps our business thrive & continue providing free recipes.