Prep the butternut squash by peeling, seeding, and cubing it into small pieces. Preheat your oven to 400°F (200°C) and spread the squash cubes on a baking sheet. Roast for 25-30 minutes until tender and caramelized, stirring halfway through.

While roasting, bring a large pot of salted water to a boil and cook the pasta until al dente, about 8-10 minutes. Reserve 1 cup of pasta water before draining.

In a large skillet over medium heat, add olive oil. After about a minute, add the Italian sausage and cook for 8-10 minutes until browned. Transfer to a plate once cooked.

In the same skillet, add the finely chopped shallot and sauté for about 2 minutes until softened. Stir in the minced garlic and cook for an additional 1-2 minutes until golden.

In a blender, combine roasted butternut squash, chicken broth, heavy cream, and nutmeg. Puree until smooth, about 1-2 minutes.

Return the sauce to the skillet with sautéed shallots and garlic over low heat. Mix in the pasta and sausage. Gradually add reserved pasta water until the desired consistency is reached.

Gently fold in the spinach and cook until wilted, about 2-3 minutes. Stir in the Parmesan cheese until melted, adjusting seasoning with salt and pepper.