Begin by bringing a large pot of well-salted water to a boil. Once boiling, add the fettuccine pasta and cook according to the package instructions until al dente. Drain the pasta thoroughly and set it aside in a large mixing bowl.
In a spacious skillet, melt the unsalted butter over medium heat. Add the minced garlic to the skillet and sauté it for approximately 1 minute, stirring frequently, until it becomes fragrant but has not browned.
Incorporate the pumpkin puree and heavy cream into the skillet. Stir the mixture continuously until it's well combined and silky smooth.
Gradually mix in the grated Parmesan cheese along with the ground nutmeg, ground cinnamon, salt, and freshly cracked black pepper. Keep stirring until the cheese is fully melted, resulting in a rich and creamy sauce.
Carefully add the drained fettuccine to the pumpkin Alfredo sauce, tossing gently to ensure each strand is evenly coated in the luscious sauce. If you find the sauce is too thick, add a splash of reserved pasta water to achieve your desired consistency.
Plate the creamy pumpkin Alfredo pasta while hot and sprinkle freshly chopped parsley on top for a burst of color and flavor. For an extra touch, you can also add a light dusting of additional Parmesan cheese.
Notes
For a lighter version, substitute heavy cream with half-and-half.