Peel the eggplant and cut it into 1/4 inch slices, discarding tips.
Combine bread crumbs, dry Parmesan cheese and some salt and pepper in one shallow bowl. Whisk eggs with a little salt and pepper in another wide, shallow bowl.
Batter eggplant slices by first pressing it in bread crumbs, then dip it in eggs, then in bread crumbs again, patting the breading down.
Preheat a skillet with 2 tbs of oil. Saute eggplant slices for about 5 minutes on each side, until soft and golden.
Cut sub along the side but not all the way through. Cut it in half, making two 6-inch subs, sliced open. Place bread on a baking sheet.
Drizzle open sub with some olive oil and a little balsamic vinegar.
Spread half of Marinara sauce on the bread and sprinkle minced basil, evenly.
Layer cooked eggplant slices and spread remaining sauce over eggplant.
Sprinkle Mozzarella cheese and then grate some Parmesan over the top.