Tips - Don't over mix, as it can cause the muffins to be tough, bake unevenly, create elongated holes (or tunnels) and/or form peaked tops. - If you prefer a different nut, you can switch them out. In addition, you may add more nuts or remove them completely if you're allergic. - Aim to fill the cups ¾ full to get muffins with nice round tops and to prevent them from spilling out over the top of the cups.
Ingredients:
1½ cups all-purpose flour
1 teaspoon baking powder
1 teaspoon baking soda
½ teaspoon salt
3 large bananas, mashed
¾ cup white sugar
1 egg
⅓ cup butter melted
½ cup pecans, chopped or crushed
Preparation:
Preheat the oven to 350 degrees Fahrenheit (175 degrees Celsius). Coat the muffin pans with nonstick spray, or use paper liners.
Sift together the flour, baking powder, pecans (or nut of choice), baking soda, and salt; set aside.
In another bowl, combine bananas, sugar, egg, and melted butter in a large bowl.
Fold in flour mixture, and mix until smooth. Scoop into muffin pans.
Bake in the preheated oven. Bake mini muffins for 10-15 minutes, and large muffins for 25-30 minutes. Muffins will spring back when lightly tapped.
Source: Me 
(Trust me bro)