Preheat the oven to 400°F (200°C).

Slice the squash in half lengthwise, scoop out the seeds, and place cut side down on a parchment-lined baking sheet.

Roast for 35–40 minutes, until tender when pierced with a fork.

Scoop out the flesh and blend or mash until smooth. Measure 2 cups (about 500 grams).

Reduce the oven temperature to 375°F (190°C) for baking the lasagna later.

In a medium bowl, combine butternut squash purée, vegan ricotta, vegan milk, salt, nutmeg, garlic powder, onion powder, and chili flakes (if using).

Stir until smooth, adding a splash of milk if needed for a spreadable consistency.

In a skillet, sauté the minced garlic in a drizzle of oil or splash of water for about 1 minute, until fragrant.

Add the spinach and cook until wilted. Drain well and press out excess moisture.

Chop the cooked spinach and mix it with vegan ricotta, salt, pepper, nutmeg, basil, and oregano.

Bring a large pot of salted water to a boil.

Cook lasagna noodles according to package instructions until al dente.

Drain and lay flat on a clean towel to prevent sticking.
 (Skip this step if using oven-ready noodles.)

Spread a thin layer of butternut squash filling on the bottom of a 9×13-inch (23×33 cm) baking dish.

Add a layer of noodles.

Spread half of the spinach filling over the noodles and sprinkle with mozzarella.

Add another layer of noodles, then spread half of the butternut squash filling and sprinkle with mozzarella.

Repeat the layers (spinach → noodles → squash), finishing with noodles topped with squash filling.

Sprinkle the top with remaining mozzarella, Parmesan, Italian seasoning, and smoked paprika.

Cover the baking dish with foil and bake for 25 minutes.

Remove the foil and bake for an additional 15–20 minutes, until golden and bubbly on top.

Let rest for 10 minutes before slicing and serving.