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

While the pasta cooks, heat the olive oil in a large skillet over medium-high heat.

Remove the casing from the Italian sausage (if needed), add it to the skillet, and cook for 6–8 minutes, breaking it into small pieces until browned and fully cooked. Transfer the sausage to a plate, leaving about 1 tablespoon of the rendered fat in the pan.

Add the diced onion to the skillet and sauté for 3–4 minutes until softened. Stir in the minced garlic and cook for 30 seconds until fragrant.

Add the pumpkin puree and stir until well combined with the onions and garlic.

Slowly pour in the chicken broth, stirring continuously until the sauce is smooth.

Reduce the heat to medium-low and stir in the heavy cream.

Add the chopped sage, thyme, nutmeg, salt, black pepper, and crushed red pepper flakes (if using). Simmer gently for about 5 minutes.

Return the cooked sausage to the skillet and stir to combine.

Gradually add the freshly grated Parmesan cheese, stirring until completely melted and the sauce is creamy.

Add the cooked pasta to the skillet and toss until every piece is coated in the sauce. If needed, add a splash of the reserved pasta water to loosen the sauce.

Taste and adjust the seasoning with additional salt, pepper, or Parmesan if desired.

Garnish with chopped fresh parsley, extra Parmesan cheese, and additional sage before serving.