HEAT oven to 350°F. Position a rack in the middle of the oven. Line 18 regular muffin cups with paper cupcake liners.
COMBINE brownie mix, oil, water and eggs in medium bowl until well blended. Fill the muffin cups half full with brownie batter. Place about 1 tablespoon chocolate chips in the center of batter.
BAKE 18 to 20 minutes or until set. Cool slightly. Remove from muffin pans and let cool completely on wire racks.
STIR together frosting and peanut butter in medium bowl. Spread over top of cooled cupcakes. Using the container of candy bits included with the frosting, decorate the top of each cupcake.