It helps to run a sharp knife around edges of brownies when removing from pans.
Preheat oven to 350°. Prepare brownie batter according to package directions for fudgy brownies, stirring peanuts into batter. Pour into 2 (24-cup) lightly greased miniature muffin pans.
Bake at 350° for 15 to 17 minutes or until a wooden pick inserted in center comes out with a few moist crumbs. Cool in pans on wire racks 5 minutes. Remove from pans to wire racks, and completely cool (about 45 minutes).
Microwave chocolate morsels and cream in a microwave-safe bowl at HIGH 30 to 45 seconds or until melted and smooth, stirring at 15-second intervals. Spread chocolate mixture over brownies, and sprinkle with peanut brittle.