1 (19.8 ounce) package fudge brownie mix
1 (10.5 ounce) package miniature marshmallows
2 cups semisweet chocolate chips
1 cup peanut butter
1 tablespoon butter
1 1/2 cups crisp rice cereal

Prepare brownie batter according to package directions for fudge-like brownies. Pour into greased 13-in. x 9-in. x 2-in. baking pan. Bake at 350 degrees F for 28-30 minutes. Top with marshmallows; bake 3 minutes longer (marshmallows will not be completely melted). Cool on a wire rack.
In a saucepan, combine the chocolate chips, peanut butter and butter. Cook and stir over low heat until smooth. Remove from the heat; stir in cereal. Spread over brownies. Refrigerate for 1-2 hours or until firm before cutting.