Preheat the oven to 375 degrees F.

Bring a pot of salted water to a boil and cook the pasta according to the package directions. Drain and place in a 9x13 inch baking dish.

While the pasta is boiling, brown the sausage in a large skillet over medium heat, breaking it apart with a wooden spoon until fully browned. Transfer to a plate.

In the same skillet, heat the olive oil over medium-low heat. Add the onions, garlic, butternut squash, and a big pinch of salt and pepper, along with the sage and crushed red pepper. Cook for 8 to 10 minutes, stirring often, until the squash is tender.

Once the squash is tender, stir in the spinach and cook until wilted. Transfer the squash and spinach mixture to the baking dish with the pasta and add the sausage back in. Toss until fully combined.

Stir in half of the cheese until mixed in with the pasta. Add the parmesan and top with the remaining cheese.

Bake for 20 to 25 minutes or until bubbly and golden.

Remove from the oven and sprinkle with more parmesan before serving.