1. Preheat oven to 375°F (190°C).
2. Cook butternut squash in boiling water until tender, then mash.
3. In a mixing bowl, combine mashed squash, ricotta cheese, and spinach.
4. Spread a thin layer of marinara sauce on the bottom of a baking dish.
5. Layer gluten-free lasagna noodles, squash mixture, mozzarella, and marinara sauce. Repeat layers.
6. Top with remaining mozzarella and Parmesan cheese.
7. Cover with foil and bake for 40 minutes. Remove foil and bake for another 20 minutes until cheese is golden and bubbly.
8. Let it cool for 10 minutes before serving.