Bring a large pot of salted water to a boil. Add fettuccine and cook according to package instructions until al dente. Reserve 1 cup of pasta water, then drain the rest and set aside.
In a large skillet over medium heat, melt the butter. Add minced garlic and sauté for about 1 minute until fragrant.
Stir in the pumpkin puree and heavy cream. Mix well, bringing the mixture to a gentle simmer.
Gradually whisk in the grated Parmesan cheese until melted and smooth. Season with nutmeg, salt, and black pepper. Adjust the seasoning to taste.
Add the cooked fettuccine to the skillet, tossing to coat the noodles with the creamy pumpkin sauce. If the sauce is too thick, add some reserved pasta water, a little at a time, until you reach the desired consistency.
Remove from heat and plate the creamy pumpkin Alfredo. Garnish with chopped fresh parsley.
Notes
Adjust seasoning to taste and add reserved pasta water for desired sauce consistency.