Cook the Gnocchi: Bring a medium pot of salted water to a boil. Add the gnocchi and cook according to package instructions until they float to the surface, usually about 2-3 minutes. Use a slotted spoon to transfer the gnocchi to a bowl and set aside.
Brown the Sausage: While the gnocchi cooks, heat olive oil or butter in a large skillet over medium heat. Add the sausage, breaking it up with a spoon, and cook until browned and cooked through, about 5-7 minutes. Remove from the skillet and set aside.
Sauté Onion and Garlic: In the same skillet, add a little more oil if needed. Sauté the chopped onion until translucent, about 3 minutes. Add the minced garlic and cook for another 30 seconds until fragrant.
Make the Pumpkin Sauce: Stir in the pumpkin puree, heavy cream, nutmeg, and sage. Mix well and let it simmer gently for 3-5 minutes, allowing the flavors to meld. Season with salt and pepper to taste.
Combine Everything: Return the browned sausage to the skillet with the pumpkin sauce. Add the cooked gnocchi and toss gently to coat everything evenly in the sauce. Warm through for 2 minutes, letting the gnocchi soak up some sauce.
Serve and Garnish: Divide the gnocchi among plates or bowls. Sprinkle generously with grated Parmesan and chopped parsley if desired. Serve hot and enjoy!