Preheat your oven to 350°F (175°C) and coat a 9x5 loaf pan with cooking spray or butter.

In a large mixing bowl, whisk together 2 cups of all-purpose flour and 1 teaspoon of baking soda until well mixed.

In another bowl, combine 1/2 cup of melted butter, 1/2 cup of granulated sugar, 1/3 cup of sour cream, 2 eggs, 3 medium mashed bananas, and 1 teaspoon of vanilla extract. Mix until blended.

Gradually pour the wet mixture into the dry ingredients and stir gently until incorporated.

In a small bowl, mix together 1/2 cup of brown sugar and 1 teaspoon of ground cinnamon. Spoon half of the batter into the prepared pan, layer with the brown sugar mixture, and top with remaining batter.

Bake for 65 to 70 minutes, or until a toothpick inserted in the center comes out clean.

Allow the banana bread to cool in the pan for 10 minutes before transferring to a wire rack.

Whisk together 3/4 cup of powdered sugar, 3 tablespoons of milk, and 1 teaspoon of vanilla extract for the drizzle. Once the bread is cool, drizzle over the top.