Begin by preheating your oven to 425°F (220°C). Toss the cubed butternut squash with one tablespoon of olive oil and a sprinkle of salt and pepper, ensuring it's well-coated.
Spread the squash evenly on a baking sheet lined with parchment paper. Roast for 25-30 minutes, or until fork-tender and slightly caramelized.
While the squash is roasting, bring a large pot of salted water to a boil. Cook the farfalle pasta according to package instructions until al dente, then drain and set aside.
In a large skillet over medium heat, cook the crumbled Italian sausage until browned and cooked through, about 8-10 minutes. Remove the sausage from the skillet and set aside.
In the same skillet, add the minced garlic and sauté for about 1 minute until fragrant. Add the fresh spinach, stirring occasionally, until wilted, about 4-5 minutes.
Pour in the heavy cream, bringing it to a gentle simmer. Stir in the grated Parmesan cheese and nutmeg, allowing the sauce to thicken slightly.
Incorporate the cooked sausage and drained pasta into the sauce, mixing well to combine. Adjust seasoning with salt and pepper as needed.
Finally, add the roasted butternut squash, gently folding it into the pasta mix or leaving it on top as a garnish.