Banana Crumb Muffins

INGREDIENTS

• 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
• 1/8 teaspoon ground cinnamon
• 1 tablespoon butter