Cinnamon Crunch Banana Bread

0 Brown the butter:In a small saucepan over medium heat, melt the ½ cup butter. Continue cooking, swirling often, until it foams and turns golden brown with a nutty aroma (about 5–7 minutes). Pour it into a large mixing bowl and let it cool for about 10 minutes.
1 Make the cinnamon crumb:In a separate bowl, mix flour, brown sugar, cinnamon, and salt. Add melted butter and stir until you get clumpy, sandy crumbs. Set aside.
2 Prepare the pan:Preheat oven to 350°F (175°C). Grease and line a 9×5-inch loaf pan with parchment paper for easy removal.
3 Make the banana bread batter:To the cooled brown butter, add brown sugar and granulated sugar and whisk until combined. Add eggs one at a time, whisking well. Stir in sour cream (or Greek yogurt), vanilla, and mashed bananas until smooth.
4 Combine dry ingredients:In another bowl, whisk flour, baking soda, baking powder, salt, and cinnamon. Add this to the wet mixture and stir gently until just combined. Don’t overmix.
5 Assemble with crumbs:Pour half of the batter into the prepared loaf pan. Sprinkle half of the cinnamon crumb evenly over this layer. Pour in the remaining batter and smooth the top. Finish with the remaining crumb mixture on top.
6 Bake:Bake for 55–65 minutes, or until a toothpick inserted into the center comes out mostly clean with just a few moist crumbs. If the top browns too quickly, tent loosely with foil around the 40-minute mark.