Wash and slice eggplant into ½ thick slices.
Brush baking pan with olive oil and place eggplant close together into an in a tight single layer. Sprinkle lightly with salt & pepper and bake for 25 to 35 minutes until eggplant is slightly brown. For more charring on top, broil while monitoring for desired brownness, (~5-10 minutes)
In a saucepan, heat olive oil and balsamic vinegar over low heat
Add chopped onion, bell pepper, garlic, and red pepper flakes saute about 3 minutes, stirring frequently to keep garlic from burning.
Add spaghetti sauce to sauteed veggies and cook about 15 minutes on medium low. Set aside until eggplant is done.
When eggplant is cooked, spread the eggplant rounds with the red sauce and veggie mixture. Top with a thin layer of shredded parmesan followed by a thin layer of shredded mozzarella, (or substitute with slices of Provolone to cover or other favorite cheese on hand).
Place the eggplant casserole dish back in the oven until cheese melts. Alternately, you can place under the broiler to give your cheese a little crispness. Sprinkle with chopped fresh basil and serve, (or, one fresh basil leaf per round if you have garden fresh basil.
Serve and enjoy!