Melt 1 cup of unsalted butter in a medium saucepan over medium heat, stirring for about 5-7 minutes until golden brown.

Preheat oven to 350°F (175°C) and grease a 9x5 inch loaf pan. In a large bowl, mix the cooled brown butter with 1 cup granulated sugar until smooth. Add 2 eggs, 1 tsp vanilla extract, and 3 mashed bananas, blending thoroughly.

In another bowl, whisk together 1.5 cups all-purpose flour, 1 tsp baking soda, 0.5 tsp baking powder, 0.25 tsp salt, and 1 tsp ground cinnamon (if using).

Gently fold the dry ingredients into the wet banana bread batter using a spatula until just combined.

In a small bowl, mix together 0.25 cup melted butter, 0.5 cup sugar, 0.5 cup all-purpose flour, and a pinch of salt until crumbly.

Pour banana bread batter into the prepared loaf pan, topping it with the sugar cookie crumble mixture. Bake for 55-65 minutes until a toothpick comes out clean.

Let the loaf cool in the pan for about 10 minutes before transferring to a wire rack.