Preheat the oven to 350°F (175°C). Lightly grease a 9×5-inch loaf pan and line it with parchment paper if desired.
In a small bowl, combine the granulated sugar with 2 teaspoons cinnamon. Set the cinnamon sugar aside.
Add the mashed bananas, melted butter, maple syrup, eggs, and alcohol-free vanilla extract to a large mixing bowl. Whisk until well combined.
Add 1 1/2 cups flour, baking soda, and salt. Fold gently until the dry ingredients are incorporated. Avoid overmixing.
To prepare the cinnamon crunch, combine the brown sugar, 1 tablespoon flour, 1 tablespoon cinnamon, and 2 tablespoons melted butter in a separate bowl. Mix until crumbly and evenly moistened.
Spoon approximately half of the banana bread batter into the prepared loaf pan and spread it into an even layer.
Sprinkle the cinnamon sugar evenly over the batter, followed by about 1/4 cup of the cinnamon crunch mixture.
Spoon the remaining batter carefully over the cinnamon layer. Gently spread it toward the edges without disturbing the filling too much.
Sprinkle the remaining cinnamon crunch generously over the top of the Cinnamon Crunch Swirled Banana Bread.
Bake for 50–60 minutes, or until the center is set and a toothpick inserted into the loaf comes out clean or with only a few moist crumbs.
If the top is browning too quickly before the center has finished baking, loosely cover the loaf with aluminum foil during the final portion of baking.
Allow the bread to cool in the pan for about 15 minutes. Transfer it carefully to a wire rack and cool for at least another 15 minutes before slicing.