Step 1: Roast the Butternut Squash
To begin, we’re going to roast the butternut squash to bring out its natural sweetness and flavor. Preheat your oven to 400°F (200°C). Spread your diced butternut squash on a baking sheet, drizzle with olive oil, and toss to coat evenly. Roast for about 25-30 minutes, or until the squash is fork-tender and lightly caramelized around the edges. If you’re in a rush, you can skip the roasting and cook it directly on the stovetop, but roasting really does elevate the flavor and sweetness of the squash.

Step 2: Cook the Pasta Shells
While the squash is roasting, cook your jumbo pasta shells according to the package instructions. Be sure to cook them just until al dente, as they will soften further when baked. Drain and set them aside to cool slightly. You can drizzle them with a little olive oil to keep them from sticking.

Step 3: Sauté the Onion and Garlic
In a medium pan, heat a little olive oil over medium heat. Add the diced onion and sauté until it becomes translucent and soft—about 3-4 minutes. Then add the minced garlic and sauté for another 30 seconds, just until fragrant.

Step 4: Wilt the Spinach
Add the chopped spinach to the pan with the onion and garlic, stirring to wilt it. Once it’s wilted down (which should only take about 2 minutes), remove the pan from the heat and set it aside.

Step 5: Make the Stuffing Mixture
Once the butternut squash is roasted and soft, transfer it to a large bowl and mash it with a fork or potato masher until smooth. If you like a bit more texture, you can leave it slightly chunky. To the mashed squash, add the ricotta cheese, Parmesan, egg, salt, pepper, sage, and nutmeg. Stir in the sautéed onion, garlic, and spinach mixture, mixing everything until well combined.

Step 6: Stuff the Pasta Shells
Take your cooked pasta shells and stuff them generously with the butternut squash mixture. Be sure not to overstuff them, as the filling can spill out during baking. Arrange the stuffed shells in a large baking dish, spreading them out evenly.

Step 7: Bake the Stuffed Shells
Pour the marinara sauce over the stuffed shells, making sure they’re all covered in sauce. Sprinkle a little extra Parmesan cheese on top if you like. Cover the baking dish with foil and bake at 375°F (190°C) for 25-30 minutes, until the shells are heated through and the sauce is bubbling.

Step 8: Serve and Enjoy!
Once the shells are done baking, remove the foil and let them cool for a few minutes. Garnish with fresh basil, if desired, and serve with extra sauce on the side. This is a dish that will have everyone coming back for seconds!