These banana bread brownies are soft and moist from ripe bananas and sour cream with crunchy walnuts! Topped with brown butter frosting they are the best indulgence.
Prep. Heat oven to 375°F. Line a 9x13" pan with parchment paper, or grease and flour. Set aside.
Cream wet ingredients. In a large bowl, beat together 1 1/2 cups sugar, 1 cup sour cream, 1/2 cup butter, and 2 large eggs until creamy. Blend in 3 ripe mashed bananas and 2 teaspoons vanilla extract.
Dry ingredients. In separate bowl, whisk (or sift) 2 cups flour, 1 teaspoon baking soda and 3/4 teaspoon salt together.
Combine. Add the flour to the banana mixture and mix just until combined. Stir in 1/2 - 1 cup walnuts if desired. Spread batter evenly into pan and bake for 20 to 25 minutes or until a toothpick comes clean.
Brown butter. Prepare the frosting as the brownies bake by heating 1/4 cup butter in a large saucepan over medium heat. Add 1/4 cup brown sugar to the melted butter and bring to a boil, stirring continuously for about 2 minutes. Remove from heat immediately.
Make frosting. Add 2 cups powdered sugar, 1 1/2 teaspoons vanilla extract and 3 Tablespoons milk. Whisk together until smooth (it will be thinner than frosting). Using a spatula, spread the brown butter frosting over brownies. This is best done when both ingredients are warm. Sprinkle chopped walnuts on top if desired.
Serve. Slice brownies into 24 squares. Serve warm, room temperature or even cold!
Notes
Variations:
Add chocolate chips to the batter before baking. Start with 1/2-1 cup.
Use Greek yogurt in place of sour cream.
Storage: Allow brownies to cool and store in a covered container for 3 days.Freezer Instructions: Place brownies on a baking sheet and freeze for 1 hour, or until hardened. Then place in a freezer container (you can stack with a piece of parchment paper in between each layer). Remove an hour before serving.