Start by bringing a large pot of salted water to a boil over high heat. Carefully add diced butternut squash to the pot. Cook for around 10–15 minutes, until tender. Use a slotted spoon to remove the squash, allowing the water to drain.

Transfer the cooked butternut squash to a blender or food processor. Blend until smooth and creamy, resembling a purée. Set the squash purée aside.

In the same pot of boiling water, add your choice of pasta and cook according to package instructions until al dente, typically 8–10 minutes. Reserve at least 1 cup of the starchy pasta water before draining the pasta.

While the pasta is cooking, heat a large non-stick skillet over medium heat. Add the spicy chicken Italian sausage, breaking it apart as it cooks. Sauté for about 5–7 minutes, until browned and cooked through. Set the sausage aside.

In the same skillet, reduce the heat to medium-low. Add whipped butter and allow it to melt. Sauté minced shallots and garlic for about 5-6 minutes until soft and fragrant.

Stir the blended butternut squash into the skillet with shallots and garlic. Season with kosher salt and freshly ground black pepper. Pour in reserved pasta water as needed to adjust sauce consistency.

Add chopped baby spinach, fresh shaved Parmesan cheese, and sage leaves to the sauce, stirring until the spinach wilts and cheese melts.

Gently toss the drained pasta and cooked sausage into the butternut squash sauce. Mix thoroughly, ensuring every piece of pasta is coated. Add more pasta water if the sauce is too thick.

Serve the creamy spicy butternut squash pasta immediately. Garnish with additional freshly shaved Parmesan if desired.