Banana Muffins w/ a Crumble Topping

The same friend that gave me the recipe for Libby's blessing day casserole brought these to it. It was such a yummy day thanks to Betsy!(who won't post her fantastic recipes so I post them for her and get to claim them as my own:)
I honestly cannot get enough of these.

* 1 1/2 cups all-purpose flour
* 1 teaspoon baking soda
* 1 teaspoon baking powder
* 1/2 teaspoon salt
* 3 bananas, mashed
* 3/4 cup white sugar
* 1 egg, lightly beaten
* 1/3 cup butter, melted
* 1/3 cup packed brown sugar
* 2 tablespoons all-purpose flour
* 1/2 teaspoon ground cinnamon
* 1 tablespoon butter

Directions:

1. Preheat oven to 375 degrees F (190 degrees C). Lightly grease 10 muffin cups, or line with muffin papers.
2. In a large bowl, mix together 1 1/2 cups flour, baking soda, baking powder and salt. In another bowl, beat together bananas, sugar, egg and melted butter. Stir the banana mixture into the flour mixture just until moistened. Spoon batter into prepared muffin cups.
3. In a small bowl, mix together brown sugar, 2 tablespoons flour and cinnamon. Cut in 1 tablespoon butter until mixture resembles coarse cornmeal. (I cheat and melt it because I lack patients) Sprinkle topping over muffins.
4. Bake in preheated oven for 18 to 20 minutes, until a toothpick inserted into center of a muffin comes out clean.