Heat 1 tablespoon olive oil over medium heat in a large sauté pan.

Add the peeled and diced butternut squash and sauté until lightly browned, about 6-7 minutes.

Add the diced red onion to the pan and sauté until tender, about 4 minutes.

Add the spicy Italian sausage, breaking it into small chunks, and cook until it is browned, approximately 3 minutes.

Stir in the minced garlic, chopped Swiss chard, and red chili flakes. Continue cooking until the chard is wilted, about 3 more minutes.

Season with salt and pepper and keep the mixture warm on low heat.

Meanwhile, bring a large pot of salted water to a boil and cook the rigatoni until al dente, about 8 minutes.

Drain the pasta, reserving ¼ cup of the pasta cooking water.

Immediately add the cooked rigatoni to the sausage and vegetable mixture in the pan.

Pour in the reserved ¼ cup of pasta water, crème fraîche, and grated parmesan. Stir well to coat the pasta, cooking for another 1-2 minutes to meld the flavors.

Adjust seasoning with salt and pepper as needed and serve hot, sprinkling extra grated parmesan on top for added flavor.