Step 1: Preheat your oven to 400°F (200°C). Toss the cubed butternut squash with olive oil, salt, pepper, and nutmeg on a large baking sheet. Roast for 25-30 minutes or until the squash is tender and the edges are golden brown.
Step 2: While the squash is roasting, bring a large pot of salted water to a boil. Cook the pasta according to package instructions until al dente. Reserve 1 cup of the pasta water before draining.
Step 3: In a large skillet, melt the butter over medium heat. Add the fresh sage leaves and fry for 1-2 minutes until crispy. Remove the sage leaves with a slotted spoon and set aside on a paper towel.
Step 4: In the same skillet with the sage-infused butter, sauté the shallots and garlic for 3-4 minutes until softened and fragrant.
Step 5: Take half of the roasted butternut squash and place it in a blender with the heavy cream and 1/2 cup of the reserved pasta water. Blend until completely smooth.
Step 6: Pour the squash purée into the skillet with the shallots. Add the cooked pasta, the remaining whole squash cubes, and the Parmesan cheese. Toss well to coat, adding more pasta water if the sauce is too thick.
Step 7: Season with additional salt and pepper if needed. Serve immediately topped with the crispy sage leaves and an extra sprinkle of Parmesan.