Begin by bringing a large pot of salted water to a rolling boil. Add the pappardelle pasta and cook according to package directions, usually about 8-10 minutes, until al dente. Stir occasionally to prevent sticking. Once cooked, reserve a cup of the pasta water, drain the rest, and set the pasta aside while you prepare the sauce.

In a medium saucepan over medium heat, combine heavy cream, whole milk, salted butter, grated Parmesan cheese, minced garlic, fresh sage leaves, ground nutmeg, salt, and pepper. Stir frequently for about 5 minutes, allowing the ingredients to meld together and the sauce to thicken slightly.

Once the sauce has thickened, remove the fresh sage leaves and discard them. Stir in the canned pumpkin, mixing well to create a uniform and creamy mixture. Cook for an additional 2-3 minutes, gently heating through while keeping the sauce at medium-low heat.

Add the drained pappardelle pasta to the pumpkin Alfredo sauce, tossing gently to coat each strand evenly. If the sauce appears too thick, gradually add some reserved pasta water until the desired creaminess is achieved.

Once well combined, plate the pasta generously and finish with an extra sprinkle of grated Parmesan cheese and a few fresh sage leaves for garnish. Serve hot.