Step 1

Preheat oven to 375 degrees F (190 degrees C). Lightly grease 10 muffin cups, or line with muffin papers.

Step 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, vanilla, cinnamon, nutmeg and melted butter. Stir the banana mixture into the flour mixture just until moistened. Spoon batter into prepared muffin cups.

Step 3

For the crumb topping: In a small bowl, mix together brown sugar, 1/4 cup flour and 1/2 teaspoon cinnamon. Cut in 2 tablespoons butter until mixture resembles wet sand. You can use your hands too to incorporate the mixture. Sprinkle topping over muffins.

Step 4

Bake in preheated oven for 15 to 20 minutes, until a toothpick inserted into center of a muffin comes out clean.