Cook the Pasta: Bring a large pot of water to a boil and salt it. Add the jumbo pasta shells and cook for 8-10 minutes until al dente. Drain and toss with olive oil to prevent sticking.

Prepare Tofu Ricotta: Blend drained extra-firm tofu in a food processor until creamy with some texture. Add nutritional yeast, garlic powder, onion powder, salt, pepper, olive oil, lemon zest, and lemon juice, processing until smooth.

Create the Pumpkin Filling: In the tofu ricotta bowl, fold in pumpkin purée, nutmeg, and vegan parmesan cheese. Mix until smooth, adjusting seasoning to taste.

Make Garlic Béchamel Sauce: In a saucepan, heat olive oil, sauté onions until translucent. Add minced garlic and cook briefly. Gradually whisk in flour, then stir in coconut milk until thickened.

Assemble the Dish: Preheat oven to 350°F. Spread a layer of béchamel in a baking dish, fill shells with pumpkin ricotta, place in the dish, drizzle with remaining béchamel, and top with sage leaves.

Bake the Stuffed Shells: Cover with foil and bake for 20 minutes. Remove foil and continue baking for 10-15 minutes until golden brown.