Crumb Topped Banana Muffins

1 1/2 cups flour
1 teaspoon baking soda
1 teaspoon baking powder
1/2 teaspoon salt
3 large ripe bananas, mashed
3/4 cup sugar
1 egg, lightly beaten
1/3 cup butter, melted

Topping
1/3 cup packed brown sugar
1 tablespoon flour
1/8 teaspoon cinnamon, to taste
1 tablespoon cold butter
1/4 cup nuts, chopped (optional)

In a large bowl, mix the flour, baking soda, baking powder, and salt. Mix bananas, sugar, egg and melted butter. Stir into dry mixture just until moistened.
Fill muffin cups 3/4 full. Combine brown sugar, flour, and cinnamon topping ingredients.
Cut in cold butter until crumbly. Sprinkle over muffins. Bake at 375 degrees Fahrenheit for about 20 minutes, until muffins test done. Cool in pan for 10 minutes.
Serves 12.