1 (10 inch) can upright baking dish
2 pounds squash, peeled and quartered
1 onion, quartered
2 tablespoons butter
1 cup chopped celery
1 (28 ounce) can mixed vegetable broth
1 (10.75 ounce) can condensed cream of mushroom soup
1 (10 ounce) can tomato soup
1 tablespoon vegetable oil
1 tablespoon finely chopped onion
1 tablespoon tomato paste
1 tablespoon Worcestershire sauce
1/2 teaspoon salt
1 teaspoon dried basil
1/2 teaspoon white sugar
Preheat the oven to 350 degrees F (175 degrees C).
Spread squash in the bottom of a medium baking dish. Cover with the onion and celery and sprinkle with butter. Season with salt, pepper and butter.
Bake uncovered at 350 degrees F (175 degrees C) for 30 minutes.
While squash is baking, line a medium baking dish with foil. Sprinkle with egg whites.
Meanwhile, heat vegetable broth over medium heat. Stir in celery, onion, tomato paste, tomato soup, tomato oil, onion, tomato paste, vegetable broth and other ingredients. Cook, stirring occasionally, for 10 minutes.
Pour squash mixture over the top and sprinkle with tomato sauce. Cover the dish with foil. Let stand for 20 minutes. Turn squash over and steam until tender. Drain excess liquid, reserve.
Meanwhile, in a small bowl, mix tomato paste and vegetable oil. Mix evenly, then stir in onion and celery until well blended. Sprinkle with tomato sauce and serve.