Banana Bread Bars

Banana Bread Bars 1-1/2 c. sugar 1 c. sour cream 1/2 c. butter, softened 2 eggs 1-3/4 (3 or 4) ripe bananas, mashed 2 tsp. vanilla extract 2 c. all purpose flour 1 tsp. baking soda 3/4 tsp. salt 1/2 c. chopped walnuts (optional) Brown Butter Frosting: 1/2 c. butter 4 c. powdered sugar 1-1/2 tsp. vanilla extract 3 tbsp. milk Heat oven to 375F. Grease and flour 15x10-inch jelly roll pan. For the bars, in a large bowl, beat together sugar, sour cream, butter, and eggs until creamy. Blend in bananas and vanilla extract. Add flour, baking soda, salt, and blend for 1 minute. Stir in walnuts. Spread batter evenly into pan. Bake 20 to 25 minutes or until golden brown. Meanwhile, for frosting, heat butter in a large saucepan over medium heat until boiling. Let the butter turn a delicate brown and remove from heat Add powdered sugar, vanilla extract and milk. Whisk together until smooth (it should be thicker than a glaze but thinner than frosting). Using a spatula, spread the brown butter frosting over the warm bars (the frosting will be easier to spread while the bars are still warm)