Saute onion in 6 tablespoons butter. Add barley and brown lightly. Pour in casserole with 1 1/2 cups chicken broth. Bake 350 deg. F. for 30 minutes. Add the mushrooms which have been sauted in the remaining butter and the rest of the chicken broth. Top with almonds and continue baking until the liquid is absorbed, approximately 45 to 60 minutes. Cook uncovered all the time.