In northern Italy, lasagna usually is made with besciamella, a white sauce, and meat ragu. In this southern version, ricotta and mozzarella cheeses are substituted for the besciamella, and a meatless tomato sauce replaces the ragu. The result is lighter and less rich, but no less delicious. You will end up with a generous amount of sauce. Serve the remainder alongside the baked lasagna, or toss it with pasta for another meal.