I recently found this recipe in the Country magazine. And I immediately tried it out. It was very easy and delicious. I ended up with about 15 cupcakes, plus had enough filling left over to make a whole cupcake out of just the peanut butter filling!
1 pkg fudge brownie mix (you will also need the ingredients listed on the back, usually just eggs and oil)
1/2 cup miniature semisweet chocolate chips (I used regular size)
1/3 cup creamy peanut butter
3 Tbsp cream cheese, softened
1/4 cup confectioner's sugar
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 paper-lined muffin cups one third full with batter. Drop filling by teaspoonfuls into the center of each cupcake. Cover with remaining batter. Bake at 350 degrees for 15-20 minutes or until a toothpick comes out clean. Cool for 10 minutes on a wire rack before removing. Dust tops with confectioners sugar. Store in refrigerator.