In a clean bowl, whisk together the 1/3 cup flour and 1/3 cup brown sugar.
Add the three tablespoons of melted butter and stir until well mixed and crumbly.
Keep in the refrigerator until ready to use.
Banana Muffins
Preheat oven to 425°F and line a 12-cup standard muffin pan with paper liners.
In a large bowl, whisk together the flour, cinnamon, baking powder, baking soda and salt. Add the pecans and lightly toss to coat the chopped pecans in the flour mixture.
In a separate bowl, whisk together the mashed bananas, eggs, melted butter, sour cream, brown sugar, white sugar and vanilla until very smooth.
Pour the wet ingredients into the large bowl with the flour and pecan mixture. Use a rubber spatula to gently mix until the ingredients are just combined and no streaks of flour remain.
Use a 4-tablespoon capacity muffin scoop to fill 12 paper muffin liners.
Evenly top each muffin with a generous tablespoonful of streusel topping.
Bake the muffins for 7 minutes at 425 degrees F. Without opening the oven door, lower the temperature to 350 degrees and continue baking for 3 minutes.
Rotate the muffin pan from front to back and continue to bake at 350 for 10-12 more minutes. The muffins should spring back when lightly touched on top when they are done.
Allow the muffins to cool in the pan for 5-10 minutes. They are delicious warm! Or cool completely on a wire rack for an additional 20 minutes.
Notes
If you don't like nuts, simply leave them out. Or replace the pecans with chopped walnuts. Mini chocolate chips or fresh blueberries would be good too!