Preheat your oven to 375°F (190°C). Lightly grease a 9×13 inch baking dish.

Bring a large pot of salted water to a boil and cook the jumbo shells according to the package directions for 'al dente.' Drain and rinse them with cold water to stop the cooking.

In a medium mixing bowl, combine the pumpkin puree, ricotta cheese, half of the parmesan cheese, egg, minced garlic, sage, nutmeg, salt, and pepper. Mix well until smooth.

Spread about 1/2 cup of sauce over the bottom of the prepared baking dish.

Fill each cooked shell with a generous amount of the pumpkin cheese mixture and place them open-side up in the baking dish.

Pour the remaining sauce over the stuffed shells and sprinkle the mozzarella cheese and remaining parmesan on top.

Cover with aluminum foil and bake for 20 minutes.

Remove the foil and bake for another 10-15 minutes until the cheese is melted and sauce is bubbling.

Let the shells stand for 5 minutes before serving.

Garnish with fresh parsley if desired.