Heat oil in a large frying pan over medium heat and sauté the zucchini and onion for 5 minutes or until soft. Put the zucchini and onion in a large bowl.
Add the sausage to the pan. Break up the sausage and cook over medium heat until no longer pink. Drain the sausage and add to the bowl. Mix zucchini, onion and sausage. Then add the remaining ingredients.
Mix well and pour into a 9x9 inch baking pan. Bake for 40 minutes at 400 degrees F. Cut into squares. Serve warm or cold.