===== Brownies =====
Mash bananas heavily in large mixing bowl.
Stir beaten eggs into bananas.
Add sugar, sour cream, butter (or margarine), vanilla, baking soda, and flour and mix until all ingredients are combined well.
Grease a 13x18 deep baking dish with pam or equivalent. Dust with flour. Pour mixture carefully, attempting to cover entire pan. Use a spreader to evenly coat the pan. Allow to settle for 5 minutes.
Bake at 375℉ for 20-25 minutes (toothpick stuck in the middle should come out clean).
===== Frosting =====
Start frosting with about 15 minutes left on the timer.
On medium heat, melt butter in small saucepan. Continue to stir butter until browned.
Add milk and vanilla to butter then slowly stir in powdered sugar until all ingredients are melted and combined. Keep warm, but do not overcook.
Pour frosting over brownies as soon as they come out of the oven. Spread evenly. Allow to cool 5-10 minutes before cutting and serving.