Ingredients
Equipment
Method
Prep
- Preheat the oven to 350°F and place an oven rack in the center. Grease and line a 9×5-inch loaf pan with parchment paper.
Make cinnamon streusel
- Combine the brown sugar, flour, ground cinnamon, and salt in a bowl. Stir in the melted butter until crumbly, then set aside.
Make banana bread batter
- Beat the softened butter, brown sugar, and granulated sugar for 2–3 minutes until light and fluffy. Scrape the sides as needed.
- Add the eggs one at a time and beat well after each addition. Mix in the vanilla extract.
- Stir in the mashed bananas and sour cream until smooth. Keep mixing just until evenly combined.
- Whisk together the all-purpose flour, baking soda, baking powder, and salt. Fold the dry ingredients into the banana mixture until just combined, taking care not to overmix.
Assemble and bake
- Spread half of the batter into the prepared loaf pan. Sprinkle half of the cinnamon streusel evenly over the batter.
- Add the remaining batter and top with the remaining streusel. Gently press the topping into the surface so it adheres.
- Bake for 60–70 minutes at 350°F, until the loaf is golden brown and a toothpick inserted in the center comes out clean. If the top browns too fast, tent loosely with foil for the last 10 minutes.
Glaze and cool
- Cool the loaf in the pan for 15 minutes, then transfer it to a wire rack. Allow it to cool until warm or room temperature.
- Whisk together powdered sugar, milk, and vanilla extract until smooth. Drizzle the glaze over the cooled loaf before slicing.
Notes
For the moistest crumb, mash the bananas until mostly smooth but still a little thick, and avoid overmixing after the flour is added. Store covered at room temperature up to 3 days or refrigerated up to 5 days; freeze sliced portions up to 3 months. For a lighter option, use reduced-fat sour cream and keep the streusel butter to the same amount for best structure.