Perogie casserole. 16 -20 frozen pierogies, Cheemo 1/2 onion, chopped 1/2 green pepper, chopped 1/2 cup cooked ham, chopped 1/4 cup milk 1 (10 1/2 ounce) can cream of mushroom soup 1/2 cheddar cheese, grated In a medium casserole dish, combine perogies, onion, pepper and ham. Mix milk and soup in a separate dish. Pour over casserole. Top with shredded cheese. Bake for 35 minutes at 350 degrees Fahrenheit.