Prepare the Zucchini:

1. Preheat the oven to 425°F and line a baking sheet with parchment paper.
2. Slice the zucchini into ⅓-inch-thick slices for even cooking.
3. Arrange the slices on the baking sheet, spray or brush with olive oil, and season with salt and pepper.
4. Roast for about 20 minutes, or until fork-tender. Let cool before assembling.

Make the Meat Sauce:

1. Heat 2 teaspoons of olive oil in a large skillet over medium-high heat.
2. Add the diced onion, minced garlic, and optional fennel seeds, cooking for 2 minutes until fragrant.
3. Add the ground meat (or vegan substitute) and cook for 8–10 minutes, breaking it apart until browned. Drain excess fat if necessary.
4. Stir in marinara sauce, oregano, chili flakes (if using), salt, and pepper. Simmer on low heat, stirring occasionally, until heated through.

Prepare the Ricotta Mixture:

1. In a medium bowl, combine ricotta cheese, the egg, nutmeg, and half of the grated Pecorino Romano cheese.
2. Stir until smooth and evenly combined.

Assemble the Lasagna:

1. Grease a 9×13-inch baking dish with olive oil.
2. Spread ½ cup of marinara sauce across the bottom of the dish.
3. Layer the zucchini slices, slightly overlapping, saving the best slices for the top layer.
4. Add half of the meat sauce over the zucchini, followed by half of the ricotta mixture.
5. Sprinkle with ¼ cup grated Pecorino Romano cheese.
6. Repeat the layers with the remaining zucchini, meat sauce, and ricotta mixture.
7. Finish with a top layer of zucchini, spreading the remaining marinara sauce evenly. Sprinkle with the remaining Pecorino Romano cheese.

Bake the Lasagna:

1. Cover the baking dish loosely with foil and bake at 425°F for 20 minutes.
2. Remove the foil and bake for an additional 5–10 minutes, or until the top is golden and bubbling.
3. Let the lasagna rest for at least 15 minutes to set before slicing and serving.