Bring a large pot of salted water to a boil. Add the fettuccine pasta and cook according to package instructions until al dente, usually about 10-12 minutes. Reserve 1/4 cup of pasta water, then drain the pasta and set aside.
In a large skillet, heat the olive oil over medium heat. Add the dried sage and sauté for about 1 minute until fragrant, being careful not to burn the herbs. Add the pumpkin puree, stirring to combine.
Pour in the chicken or vegetable broth and heavy cream. Stir well to create a smooth sauce. Reduce heat to low and let the mixture simmer for 3-5 minutes, allowing the flavors to meld.
Stir in the grated Parmesan cheese until melted and fully incorporated. Season with salt and freshly ground pepper to taste. If the sauce feels too thick, add a splash of the reserved pasta water to reach your desired consistency.
Add the cooked fettuccine directly into the skillet, tossing gently to coat every noodle evenly with the creamy pumpkin sage sauce. Warm everything together for a minute or two.
Plate the pasta and garnish with fresh sage leaves for a pop of color and an extra layer of herbal aroma. Serve immediately for the best experience.