Preheat oven to 350°.
Combine sugar and butter in a large bowl; beat with a mixer at medium speed until blended. Add egg and egg white, 1 at a time, beating just until blended. Stir in vanilla.
Lightly spoon flour into dry measuring cups; level with a knife. Combine flour and next 3 ingredients. Add flour mixture to butter mixture, stirring just until blended. Stir in chocolate minichips.
Spread batter into an 8-inch square baking pan coated with cooking spray. Bake at 350° for 22 minutes or just until a wooden pick inserted in center comes out clean (do not overcook). Cool completely on a wire rack.
Spoon ice cream into a large freezer-safe container. Crumble brownies over ice cream. Add peanuts and caramel topping; stir until well blended. Cover and freeze until firm.