Brown sausage and set. Peel eggplant and cut into ¼ inch slices, then steam until crisp tender. Butter a 9 x 13 inch pan (to cook in oven) or heavy-duty foil (to grill). Make layers of eggplant, salt and pepper to taste, sausage and cheeses, then repeat. Sprinkle top with grated parmesan and oregano. Bake in oven at 325 degrees for 25 minutes; if grilling, cook for 30 minutes over medium coals. Leave uncovered for half the cooking time.