Shrimp-Rice Casserole 1 finely chopped onion 1/2 green bell pepper, finely chopped 1 stalk celery, finely chopped 3 cups cooked rice 1 can cream of mushroom soup 1/2 can milk 1 (12 ounce) package frozen shrimp,     cooked and finely chopped Sauté onion, bell pepper and celery in a small amount of oil. Remove from heat, then add rice, mushroom soup which has been diluted with milk, and shrimp, cooked and finely chopped. Please mixture in a buttered casserole dish. Sprinkle 1/2 cup grated Cheddar cheese over the top and bake, uncovered, at 300 degrees F for one hour.