Bring a large saucepan of salted water to a rolling boil, then add the jumbo pasta shells. Cook them until just al dente, about 7-9 minutes, then drain and toss with olive oil.

Preheat your oven to 350°F (175°C) and grease a baking dish.

Drain the tofu and combine in a food processor with nutritional yeast, garlic powder, onion powder, salt, black pepper, olive oil, lemon zest, lemon juice, and red pepper flakes. Pulse until slightly smooth.

Gently fold the tofu ricotta with canned pumpkin and nutmeg in a bowl, and adjust seasonings.

In a frying pan, heat olive oil and sauté the onion until softened. Add minced garlic and cook until fragrant.

Add all-purpose flour to the mixture. Whisk and gradually add coconut milk until the sauce thickens.

Blend the sauce with salt and pepper until smooth.

Pour some béchamel sauce into the baking dish, stuff each shell with pumpkin ricotta, and arrange them in a single layer.

Drizzle remaining sauce over stuffed shells and sprinkle with fresh sage leaves.

Bake for 22-25 minutes, until golden and bubbling. Let cool slightly before serving.