In 6 tablespoons melted butter, saute 1/2 cup chopped onion. Add 1/2 cup barley; brown. Put in casserole and add 1 1/2 cups chicken broth. Cover and bake 30 minutes at 350 degrees. Add 1 1/2 cups chicken broth and 1 1/2 cups mushrooms. Bake 40 minutes longer at 350 degrees or until all liquid is absorbed. Remove lid the last half hour.