Preheat oven to 350°
Line baking sheet with parchment paper.
In a medium bowl combine brownie mix, butter, cream cheese and egg. Stir until dough comes together, it will be very thick and sticky. I used my hands.
Form rounded tablespoons sized portions of dough into balls, placing on baking sheet about 2 inches apart, making an indentation with your thumb in the center of each.
In another bowl stir together peanut butter and powdered sugar. Form peanut butter into teaspoon sized balls and press into the indentations in the brownie cookies.
Press peanut butter down slightly because the peanut butter won't spread and you don't want the cookies to be too tall.
Bake for 10-12 minutes until edges are set.
Transfer to wire rack to cool.
When cooled top each cookie with about a tablespoon of chocolate frosting.
I used my recipe for chocolate frosting, but you could also use canned frosting.