Slice the eggplants into ¼ inch rounds and sprinkle with salt. Let them sit in a colander for about 30 minutes. This process, known as 'sweating', draws out excess moisture and bitterness from the eggplants.

After 30 minutes, rinse the eggplant slices under cold water and pat them dry with paper towels.

Heat 2 tablespoons of olive oil in a large skillet over medium heat. Add the eggplant slices in batches, cooking for about 3-4 minutes on each side until golden brown. Remove and set aside.

In the same skillet, add 2 tablespoons of olive oil and heat over medium heat. Add the chopped onion and sauté for about 5 minutes until translucent.

Add the minced garlic and cook for an additional minute until fragrant. Be careful not to burn the garlic.

Stir in the crushed tomatoes, oregano, basil, sugar, salt, and black pepper. Bring the sauce to a simmer and let it cook for about 15 minutes, stirring occasionally.

In a mixing bowl, combine the ricotta cheese, beaten egg, grated parmesan cheese, salt, black pepper, and chopped parsley. Mix well until all ingredients are fully incorporated.

Preheat your oven to 375°F (190°C). In a 9x13 inch baking dish, spread a thin layer of marinara sauce on the bottom.

Layer half of the eggplant slices over the sauce, followed by half of the ricotta mixture, and then a layer of marinara sauce. Sprinkle with 1 cup of mozzarella cheese.

Repeat the layers with the remaining eggplant, ricotta mixture, marinara sauce, and finish with the remaining mozzarella cheese on top.

Cover the baking dish with aluminum foil (to prevent burning) and bake for 25 minutes. Remove the foil and bake for an additional 15 minutes until the cheese is bubbly and golden.

Once baked, let the lasagna cool for about 10 minutes before slicing. This resting time allows the layers to set, making it easier to serve.

Garnish with additional fresh parsley if desired and serve warm.