In a large skillet, heat 2 tablespoons of olive oil over medium heat. Add 1 chopped onion and sauté for about 3 minutes until it softens. Then, incorporate 2 cloves of minced garlic and 4 cups of fresh spinach. Stir frequently for 3-4 minutes until the spinach is wilted and vibrant. Remove from heat and set aside to cool slightly.

In a mixing bowl, combine 1 cup of pumpkin puree, 1 cup of plain unsweetened milk, ½ teaspoon of ground cinnamon, ¼ teaspoon of nutmeg, and a pinch of salt. Use a whisk to blend these ingredients until smooth and creamy.

In a separate bowl, mix together 15 ounces of ricotta cheese, 1 large egg, 1 cup of shredded mozzarella cheese, ½ cup of grated Parmesan cheese, and 1 teaspoon each of dried oregano and basil. Gently fold in the cooled spinach mixture.

Preheat your oven to 400°F (200°C). In a prepared 9x13 inch baking dish, spread a layer of the pumpkin filling on the bottom. Then, add a layer of no-boil lasagna noodles followed by half of your ricotta mixture. Top with another layer of pumpkin filling, followed by more noodles, and repeat the process. Finish with a final layer of noodles topped with the remaining pumpkin filling and remaining mozzarella.

Cover the baking dish with foil and bake in your preheated oven for 25 minutes. After this time, carefully remove the foil and continue to bake for an additional 15-20 minutes until the top is golden and bubbly.

Remove the lasagna from the oven and let it cool for about 25 minutes before slicing. Garnish your servings with fresh basil or parsley.