Banana Bread Bars with Brown Butter Frosting

Ingredients

• 1 1/2 cups white sugar
• 1 cup sour cream
• 1/2 cup butter, softened
• 2 eggs
• 1 3/4 cups mashed ripe bananas
• 2 teaspoons vanilla extract
• 2 cups all-purpose flour
• 1 teaspoon baking soda
• 3/4 teaspoon salt
• 1/2 cup chopped walnuts (optional)
• 1/2 cup butter
• 4 cups confectioners’ sugar
• 3 tablespoons milk
• 1 1/2 teaspoons vanilla extract