Bring a large pot of salted water to a boil. Add your pasta and cook until al dente, according to the package directions. Reserve about ¼ cup of pasta water before draining. This starchy water helps loosen and bind the sauce later.
In a large skillet over medium heat, melt the butter. Add the minced garlic and sauté for about 1–2 minutes until fragrant. Be careful not to let it brown, or it can taste bitter.
Whisk in the pumpkin puree and cream. Stir well to combine until the sauce looks smooth and creamy. Let it simmer gently for 3–5 minutes to warm through and thicken slightly.
Add salt, pepper, nutmeg (if using), and parmesan cheese. Stir until the cheese is melted and fully incorporated. If the sauce seems too thick, add a splash of the reserved pasta water to loosen it up.
Add the drained pasta directly into the skillet and toss gently to coat. Keep the heat on low and toss until everything is well mixed and heated through. Use tongs for easier mixing.
Serve the pasta immediately, topped with more grated parmesan and chopped parsley if desired. For extra fall flair, sprinkle with a tiny pinch of cinnamon or crushed walnuts.