Preheat oven to 350 degrees. Grease mini muffin pans. Do not use paper liners. Combine brownie mix and ingredients on box until well blended. Stir in 1 cup toffee bits. Spoon into prepared pans. Bake 15 minutes or until toothpick comes out clean. Cool brownies on wire rack for 15 minutes, then remove from pan and cool completely. Blend frosting and caramel. Chill 20 minutes. Pipe frosting on brownies. Sprinkle with remaining toffee.