In a large mixing bowl stir together all remaining ingredients except croutons. When vegetables are cooked tender crisp, stir into the sauce mixture and pour into an oven safe baking dish. Top with croutons just before baking. Bake uncovered at 350° for 40 minutes or until bubbly.
** this dish can be assembled in advance, covered and refrigerated. If refrigerated, allow the casserole to come to room temperature before baking or allow extra baking time.