Preheat oven to 350. For brownies, pour boiling water over butter & oats in a bowl, cover and let stand for 20 minutes. After 20 minutes mix the remaining dry ingredients for brownies and add to oat mixture. Then add your 2 eggs and blend well then pour into 13x9 baking dish.
Bake at 350 for 35 minutes or until brownies test done in center and toothpick inserted comes out clean. Make frosting now. Melt butter in a medium saucepan, stir in brown sugar & salt. Cook 2 minutes on low heat stirring constantly. Add milk, stirring until mixture comes to a boil.
Remove from heat and gradually stir in powdered sugar and vanilla and mix well, add more milk if frosting is too thick. Fold in coconut. Spread frosting evenly over hot brownies and serve.