Gently simmer the tomato sauce.
Trim the eggplant and cut into rounds; Sprinkle the eggplant with salt and place in a colander for 20 minutes; Rinse slices and pat dry.
Heat a generous layer of olive oil in a frying pan and fry the eggplant slices on both slides until they are golden, then dry on paper towels.
Place a layer of the eggplant slices at the bottom of a well-buttered baking dish, cover with slices of ham, a few tablespoons of tomato sauce, pepper, and generously sprinkle with Parmesan cheese. Repeat the layers until the ingredients are all used.
Dot the surface with butter and bake in a slow oven at 325 for about an hour.
Serve hot.
*By Italian standards, the sauce should be homemade, fresh and flavorful, but can be prepared with the simplest of ingredients, such as olive oil, butter, onion, garlic and herbs.
