Prep the zucchini: Slice zucchini lengthwise into even planks using a sharp knife or mandoline. Lay them on sheet pans or a rack, sprinkle both sides with salt, and let them sit for 20–30 minutes to release moisture. Pat dry thoroughly with paper towels.

Optional pre-cook step: For sturdier layers, lightly grill, pan-sear, or bake the zucchini planks for 3–4 minutes per side until just tender. Lay on clean towels to wick off excess moisture.

Make the meat sauce: Heat olive oil in a skillet over medium heat. Add the onion and cook 3–4 minutes until translucent. Stir in garlic for 30 seconds. Add the ground beef, breaking it up, and cook until browned. Drain excess fat if needed.

Season and simmer: Stir in marinara, tomato paste, oregano, basil, and red pepper flakes. Taste and season with salt and pepper. Simmer 8–10 minutes to thicken slightly. You want a rich, spoonable sauce, not watery.

Mix the cheeses: In a bowl, combine ricotta, egg, Parmesan, 1 cup mozzarella, herbs, nutmeg (if using), and a pinch each of salt and pepper. Stir until smooth.

Assemble: Preheat oven to 375°F (190°C). Lightly oil a 9x13-inch baking dish. Spoon a thin layer of meat sauce on the bottom. Add a layer of zucchini planks, slightly overlapping. Spread on half the ricotta mixture, then more sauce. Repeat layers: zucchini, remaining ricotta, more sauce. Finish with a final layer of zucchini and the remaining meat sauce.

Add cheese topping: Sprinkle the remaining 1 cup mozzarella across the top. Add a little extra Parmesan if you like a deeper crust.

Bake: Cover loosely with foil (tent it so it doesn’t stick to the cheese). Bake 25 minutes, then uncover and bake another 15–20 minutes until bubbly and golden.

Rest and serve: Let the lasagna sit for 10–15 minutes to set. Slice with a sharp knife and serve with fresh basil.