Fill a large pot with water, add salt, and bring to a boil. Add the jumbo pasta shells and cook until they are al dente, following package instructions. Drain the shells and set them aside to cool before handling. This prevents them from tearing when stuffed later.

While the shells are cooking, make the pumpkin sauce. In a large sauté pan over low heat, melt the butter. Add the minced garlic and cook, stirring for 2-3 minutes until aromatic. Sprinkle in the ground nutmeg and continue stirring for another minute. Whisk in the pumpkin puree, half and half, grated parmigiano reggiano, chopped rosemary, kosher salt, and black pepper. Stir well until the sauce becomes smooth and cohesive. I like to let the sauce simmer gently for a few minutes to help the flavors meld.

In a medium mixing bowl, combine the ricotta cheese, mozzarella cheese, grated parmigiano reggiano, chopped fresh rosemary, pinch of nutmeg, salt, and black pepper. Mix until the filling is thoroughly blended and smooth. For extra flavor, I sometimes add a tiny squeeze of lemon juice to the filling mixture.

Fill each cooled pasta shell with the cheese filling from Step 3 using a spoon or a piping bag. Arrange the stuffed shells seam side up in a baking dish over the prepared pumpkin sauce from Step 2. Optionally, sprinkle extra mozzarella cheese on top if you prefer a cheesier finish.

Preheat your oven to 400°F (200°C). Bake the assembled shells with sauce for 20 minutes, or until the cheese is bubbly and the dish is heated through. Remove from the oven and let the dish cool for several minutes; the sauce will thicken as it sets. I like to let it rest for at least 10 minutes before serving—this helps hold its shape and enhances the creamy texture.