Preheat the oven to 400 degree F. Line a parchment paper on a baking tray and keep it aside.
Prepare the marinara sauce: Heat a saucepan with olive oil, add yellow onion and garlic. Saute for 2-3 minutes until onions turn translucent. Add in the tomato paste, crushed tomatoes, Italian seasonings, sugar, red chili flakes, salt and pepper. Let the sauce simmer for 10-15 minutes until the sauce thickens a bit. Remove the saucepan from the heat and add the fresh basil leaves and set aside.
Cut the ends of eggplant and slice the eggplant a little thick and season them with salt. Allow to rest for 10 minutes. Pat them dry to remove the water on them. Add black pepper. Brush the eggplant slices with olive oil and arrange them on the prepared baking tray. Bake for 20 - 30 minutes by flipping halfway through and lightly browns.
Meanwhile in a medium bowl combine; ricotta cheese, parmesan cheese, egg, salt and pepper.
Spread a thin layer of prepared marinara sauce over a 9X13 baking dish. Arrange a single layer of baked eggplant slices over the sauce. Spread a layer of ricotta mixture, add ¼ cup mozzarella cheese and then some sauce, repeat the same for the other layer. End the final layer with marinara sauce and spread the mozzarella cheese.
Cover the baking dish with foil and bake for 30 - 35 minutes. Once done remove the foil and broil for 2 minutes.
Garnish the lasagna with parsley and allow the lasagna to cool for 10 minutes and then slice them and serve.