Heat olive oil in a skillet over medium heat. Add chopped onion, seasoning with salt and pepper, and sauté for 3 minutes until translucent. Stir in minced garlic and continue cooking for 1 minute. Add fresh spinach and cook until wilted, around 4 minutes. Remove from heat and let cool slightly.

In a mixing bowl, combine pumpkin puree with almond milk, ground cinnamon, nutmeg, and kosher salt. Whisk until smooth and creamy.

In another bowl, blend ricotta cheese, egg, shredded mozzarella, grated Parmesan, dried oregano, and a pinch of salt and pepper. Gently fold in cooled spinach mixture.

Preheat the oven to 400°F (200°C). Grease a 9x13 inch baking pan. Spread a layer of pumpkin filling. Place 5 no-boil noodles over the filling, then add half of the ricotta spinach mixture, followed by half of the shredded mozzarella. Repeat layers and finish with remaining noodles and pumpkin filling.

Cover lasagna with foil, ensuring it's tightly sealed. Bake for 25 minutes. Remove foil and bake for another 15-20 minutes until golden brown and bubbling.

Allow lasagna to cool for 25 minutes before serving. Sprinkle with fresh herbs before plating.