These Banana Crumb Muffins feature a cinnamon-brown sugar streusel topping on an ultra-moist muffin. Quick and easy to make, they're great for breakfast or a light after dinner treat with a cup of coffee or tea.
Preheat the oven to 375 degrees F. Line 12 muffin cups with paper liners.
In a large bowl, mix together the flour, baking powder, baking soda, salt, and cinnamon. Blend in the bananas, sugar, milk, egg, and vanilla until just combined.
Spoon batter into prepared muffin cups, filling each about 3/4 full.
Make the crumb topping: In a small bowl, mix together the brown sugar, flour, and cinnamon. Using your hands, press in the butter until the mixture resembles coarse crumbs, then sprinkle topping over muffins.
Bake in the preheated oven until a toothpick inserted into the center comes out clean, 18 to 20 minutes.