Food.com has an easy recipe for making mixed vegetable casserole that calls for just seven ingredients and can be easily adjusted to suit specific dietary needs and individual tastes. It requires frozen mixed vegetables, along with additional seasonings and sauce ingredients.
To make this recipe, cook a 20 ounce package of frozen mixed vegetables according to the instructions. Drain them thoroughly and place them into a large bowl. Add one cup of chopped onion, one cup of chopped celery, one cup of shredded cheddar cheese and one cup of mayonnaise. Stir well, and then spoon the mixture into a greased 11x7x1 1/2-inch baking dish.
Mix 1 1/2 cups of Ritz cracker crumbs and 1/2 cup of melted butter or margarine. Sprinkle this mixture over the top of the casserole and place it in 350 degree Fahrenheit oven for 30 to 35 minutes or until done. Serve hot.
The majority of reviewers for this recipe say they would make it again. One person suggested using an additional bag of frozen vegetables and another mentioned that substituting sour cream or plain yogurt for mayonnaise would be a healthy upgrade. Another person advised that leftover vegetables from other meals can be used in place of the frozen ones to give this recipe even more versatility.