In a large bowl, combine the flour, brown sugar and baking powder. In a small bowl, combine the bananas, milk, oil and egg. Stir into dry ingredients just until moistened. Fold in 1 cup toffee bits.
Fill greased muffin cups three-fourths full. Sprinkle with remaining toffee bits. Bake at 350° for 18-20 minutes or until a toothpick inserted in the center comes out clean. Cool for 5 minutes before removing from pan to a wire rack. Serve warm.