Preheat your oven to 375°F (190°C).

In a large pot, bring salted water to a boil and cook the jumbo pasta shells according to package instructions until al dente, usually 8-10 minutes. Drain and rinse under cold water to stop cooking.

In a mixing bowl, blend together pumpkin puree, ricotta cheese, half of the shredded mozzarella, grated Parmesan, garlic powder, dried sage, ground nutmeg, salt, black pepper, and the egg until smooth.

Spread 1 cup of marinara sauce evenly on the bottom of a 9x13-inch baking dish.

Carefully fill each shell with the pumpkin ricotta mixture and place them opening side up in the baking dish.

Pour the remaining marinara sauce over the stuffed shells and sprinkle the rest of the mozzarella on top.

Drizzle a little olive oil over the top and cover with foil. Bake for 25 minutes.

After 25 minutes, remove the foil and bake for an additional 10 minutes until golden and bubbly.

Let the dish rest for 5 minutes before serving. Garnish with fresh parsley or sage.