Slice and boil 4 large yellow squash until tender. Drain. While squash are cooking, fry 1/2 pound sausage. Add 1 small onion, chopped. Pour off all grease. Mix sausage, onion and squash. Add together 2 eggs and 1/2 cup milk, then mix with above. Top with grated Cheddar cheese. Bake at 350 degrees for 20 to 30 minutes in a 1 1/2 quart casserole dish.