01 - Preheat oven to 400°F (200°C). Line a baking sheet with parchment paper.
02 - Arrange squash slices on the prepared baking sheet, drizzle with 1 tablespoon olive oil, season with salt and pepper, and roast for 20 minutes until tender. Set aside. Reduce oven temperature to 375°F (190°C).
03 - Heat remaining olive oil in a large skillet over medium heat. Cook onion for 3-4 minutes until translucent, then add garlic and spinach; sauté until spinach wilts. Remove from heat.
04 - In a mixing bowl, combine ricotta, egg, 1 cup mozzarella, and half the Parmesan cheese. Stir in the spinach mixture and season with salt and pepper.
05 - In a separate bowl, blend tomato passata with oregano, basil, salt, and pepper.
06 - Spread a thin layer of tomato sauce in a 9x13-inch baking dish. Layer gluten-free lasagna noodles, followed by ricotta-spinach mixture, roasted squash, and sauce; repeat for 2–3 layers, finishing with noodles and remaining sauce.
07 - Sprinkle with remaining mozzarella and Parmesan cheese.
08 - Cover with foil and bake for 30 minutes. Uncover and bake an additional 15–20 minutes until golden and bubbling.
09 - Let stand for 10–15 minutes before slicing and serving.