Layer half of the potatoes, carrots, celery, and onion in a 3 quart casserole dish. Crumble half of the uncooked beef over vegetables. Sprinkle with 1/2 teaspoon each of thyme, salt and pepper. Do the same with one more layer on top of this.
Top with tomatoes. Cover and bake at 350°for about an hour and 15 minutes until vegetables are tender.
Top with cheese and return to the oven just long enough to melt it.
This is a complete meal with all of your important food groups so there is no need to prepare any side dishes to go with it.