Preheat oven to 350°. Prepare brownie batter according to package directions; stir in chocolate chips.
For filling, in a small bowl, beat peanut butter, cream cheese, egg and sugar until smooth.
Fill mini paper-lined muffin cups one-third full with batter. Drop filling by teaspoonfuls into the center of each cupcake. Cover with remaining batter.
Bake 15-20 minutes or until a toothpick inserted in brownie portion comes out clean. Cool 10 minutes before removing from pan to a wire rack to cool completely.