Preheat oven to 400°F (200°C). On a baking sheet, toss the cubed butternut squash with 1 tbsp of olive oil, salt, and pepper. Roast for 20-25 minutes until tender and lightly caramelized.

Bring a large pot of salted water to a boil. Cook pasta according to package directions until al dente. Reserve 1 cup of pasta water before draining.

While the pasta cooks, heat 1 tbsp olive oil in a large skillet over medium-high heat. Add the sausage and cook, breaking it apart, until browned. Remove sausage from the skillet and set aside.

In the same skillet, sauté the chopped onion until soft. Add the minced garlic and chopped sage, cooking for another minute until fragrant.

Stir in the heavy cream and bring to a simmer. Add the grated Parmesan and nutmeg, stirring until the cheese is melted and the sauce is smooth.

Return the cooked sausage to the skillet. Add the roasted butternut squash and the drained pasta. Toss everything to combine, adding reserved pasta water as needed to reach your desired sauce consistency. Season with salt and pepper to taste.

Serve immediately, garnished with extra Parmesan and fresh sage leaves.