Preheat oven to 375º F. Spray a 24-cup mini muffin tin with cooking spray or line with paper liners.
In a medium bowl, combine flour, baking soda, baking powder and salt.
In a large mixing bowl, combine mashed bananas and shredded zucchini. Beat in egg, Truvia (or sugar) and 1/2 cup melted coconut oil.
Stir the flour mixture into the banana-zucchini mixture. Don't overmix! Spoon batter into mini muffin tins.
In a small bowl, melt 1 Tbsp. coconut oil. Stir in 2 Tbsp. flour, brown sugar and cinnamon. Sprinkle crumb mixture over the tops of each muffin.
Bake for about 15 minutes or until tops spring back when pressed. Let cool on wire rack and then pop out and enjoy! (I like to put them on the counter in an airtight container for one day and then split up what's left, putting half in the fridge and the other half in the freezer for later.)