When eggplant discs are tender, carefully remove baking sheet from oven and set aside.
Add ½ cup marinara sauce to greased baking dish. Spread marinara out to cover bottom of dish, making sure to reach each corner.
Arrange 6 eggplant discs on top of marinara sauce in one flat, even layer, being careful not to stack or overlap discs.
Cover eggplant layer with ¾ cup marinara, spreading marinara out to cover eggplant evenly.
Top marinara layer with 6 mozzarella discs, placing each on top of one eggplant disc beneath marinara.
Stack remaining 6 eggplant discs on top of mozzarella discs.
Cover new eggplant layer with remaining ¾ cup marinara, spreading marinara out to cover eggplant evenly.
Top new marinara layer with remaining 6 mozzarella discs, placing each on top of one eggplant disc beneath marinara.
Place baking dish in oven still heated to 400° Fahrenheit. Bake 10 minutes or until mozzarella is warm and melted.
Optional: Turn broiler on high. Broil eggplant parmesan 2 to 3 minutes or until top layer of mozzarella is just browned.
When cheese has melted, carefully remove baking dish from oven. Portion eggplant parmesan onto serving plates and garnish with fresh basil. Serve warm with desired sides.