1. Preheat the oven to 350 degrees f. Line a cookie sheet with parchment paper.
2. In a stand mixer or a large bowl with an electric mixer, cream together butter and sugar.
3. Add egg and peanut butter and continue to mix on low speed.
4. Add dry ingredients to the wet ingredients slowly and combine until a soft dough forms.
5. Drop 8 to 10 large scoops of dough onto the prepared baking sheets. Leave at least 2" between each cookie dough ball.
6. For best results, bake cookies at 350 for 12 minutes or until the edges start to brown. Place on a wire rack to allow the cookies to cool quickly.
7. In a small bowl combine frosting and 2 tablespoons of peanut butter.
8. Scoop the frosting mixture into a piping bag with 1A tip and cover each cookie with the frosting.
9. Roughly chop up the mini Reeses cups.
10. Place the Reese's pieces and peanut butter cups on top of the cookies.