This is DE-licious! It tastes like a veggie lasagna, but without the noodles. I think it could be a complete meal for a vegetarian, or you could throw some cooked Italian sausage in and call it done. I found it in  Better Homes & Gardens Italian Cookbook, which is out of print.

This recipe calls for a small can of tomatoes and a cup of cheese. We double both and like it better that way.

Zucchini and Cauliflower Skillet
1/4 cup chopped onion
1 clove garlic, minced
2 T olive oil or cooking oil
1-7.5 oz can diced tomatoes
1 T snipped parsley
1 T tomato paste
1/2 t salt
1/2 t dried oregano, crushed
1/4 t pepper
2 medium zucchini, bias sliced 1/2" thick
2 cups cauliflowerets
1/2 cup water
1 cup shredded mozzarella cheese (4 oz.)

In saucepan, cook onion and garlic in oil till onion is tender. Stir in undrained tomatoes, parsley, tomato paste, salt, oregano, and pepper. Boil gently, uncovered, for 10-15 minutes or till slightly thickened, stirring occasionally. Meanwhile, in 10-in. covered skillet cook zucchini and cauliflowerets in water over medium heat about 5 minutes or till crisp-tender. Drain.

Pour tomato mixture over vegetables. Cover and cook for 4 to 5 minutes or till heated through. Sprinkle with mozzarella cheese. Cook, uncovered, about 3 minutes longer or till cheese is melted. Sprinkle with additional snipped parsley, if desired.

Makes 4-6 servings.