Prep the eggplant: Heat the oven to 425°F (220°C). Slice eggplants into 1/2-inch rounds or long planks. Lay on two sheet pans, brush with 2 tablespoons olive oil, and season with salt and pepper. Roast for 20–25 minutes, flipping once, until tender and lightly browned. Set aside and lower oven to 375°F (190°C).

Brown the sausage: While eggplant roasts, heat 1 tablespoon olive oil in a large skillet over medium-high. Add sausage, breaking it up with a spatula. Cook until browned and cooked through, about 6–8 minutes. Transfer to a bowl and leave 1 tablespoon drippings in the skillet.

Make a quick sauce: In the same skillet, add onion with a pinch of salt. Cook 3–4 minutes until softened. Stir in garlic for 30 seconds. Add crushed tomatoes, tomato paste, Italian seasoning, and red pepper flakes if using. Simmer 5–7 minutes to thicken slightly. Taste and season with salt and pepper. Stir in chopped basil or parsley. Fold the sausage back into the sauce and remove from heat.

Mix the cheese layer: In a bowl, combine ricotta, egg, half of the Parmesan, a pinch of salt and pepper. Stir until smooth.

Assemble the bake: Lightly oil a 9x13-inch baking dish. Spread a thin layer of the sausage-tomato mixture on the bottom. Add a layer of roasted eggplant, then dollops of the ricotta mixture, and a sprinkle of mozzarella. Repeat layers until everything is used, finishing with sauce and the remaining mozzarella. Top with the remaining Parmesan.

Bake: Cover loosely with foil and bake at 375°F (190°C) for 20 minutes. Uncover and bake another 10–15 minutes until bubbly and browned on top. Let rest 10 minutes before slicing so it sets.

Portion for meal prep: Cut into 6–8 squares and transfer to airtight containers. Add extra fresh herbs on top if you like.