• Preheat oven to 375 degrees.
• Spray a 8 x 8 inch baking pan with nonstick baking spray. Line the baking pan with parchment paper.
• Cut the parchment paper long enough to hang over the sides of the baking dish.
• Use an electric mixer to blend the sugar, sour cream, butter, and eggs until creamy.
• Add the mashed bananas and vanilla to the mixing bowl with the sugar mixture.
• Continue mixing until all ingredients have been blended. In a second bowl whisk the flour, baking soda and salt together.
• Slowly add the flour mixture to the butter mixture. Use the electric mix to blend all ingredients together.
• Stir to mix in the walnuts. Scoop the batter in the baking pan.
• Use an offset spatula to even the top of the batter. Bake at 375 degrees for 22-25 minutes.
• Insert a toothpick in the center to make sure that it is done.

Frosting:

• Melt the butter over medium heat until it starts to boil. Watch as the butter starts to turn to a light brown color.
• Immediately take the pot off of the heat.
• Use a whisk to stir in the powdered sugar, vanilla, and milk until it is smooth. (The texture of the frosting will be between a glaze and a thick frosting.)
• As soon as you remove the bars from the oven, spread the frosting on top.
• Set aside until serving.