Preheat the oven to 350°F (175°C) and grease a 9×5 inch loaf pan with butter.
In a small bowl, mix together the granulated sugar and 2 teaspoons of cinnamon. Set aside.
In a large bowl, combine the mashed bananas, melted butter (or coconut oil), maple syrup, eggs, and vanilla extract. Stir until smooth and well combined.
Add the flour, baking soda, and salt to the wet mixture. Stir gently until just combined. Do not overmix.
In a separate bowl, prepare the cinnamon crunch by mixing the melted butter, brown sugar, flour, and cinnamon until crumbly.
Pour half of the banana bread batter into the prepared loaf pan and spread evenly.
Sprinkle the cinnamon sugar mixture evenly over the batter.
Add 1/4 cup of the cinnamon crunch mixture over the cinnamon sugar layer.
Spoon the remaining batter over the top and spread gently to cover.
Sprinkle the remaining cinnamon crunch mixture evenly over the top.
Bake for 50–60 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs.
Remove from the oven and let the bread cool in the pan for about 30 minutes before slicing.