Preheat the oven to 375 degrees and line a 12-muffin tin with muffin papers.
In a large bowl, combine 1 1/2 cups all-purpose flour, 1 teaspoon baking soda, 1 teaspoon baking powder, 1/2 teaspoon salt and 3/4 teaspoon ground cinnamon.
In another large bowl, beat the bananas, 1/2 cup granulated sugar, 1 large egg, 1/3 cup coconut oil and 1 1/2 teaspoons pure vanilla extract.
Gently combine the wet and dry ingredients.
Pour mixture into the muffin tin (I used a 1/4 cup for each tin)
For the crumble topping, mix the brown sugar, flour and cinnamon in a small bowl. Cut in the butter until evenly distributed (I used a whisk to smash the butter and combine with the dry ingredients.) Sprinkle topping over muffins.
Cook for 18-20 minutes or until an inserted toothpick comes out clean.
Notes
P.S.For a reduced sugar alternative, skip the cinnamon sugar topping!
P.P.S. I actually had enough batter for 13 muffins. As much as I wanted to just eat the leftover batter, I put it into a second muffin tin 🙂