Preheat oven to 400°F.
Line a rimmed baking sheet with foil. Place the spaghetti squash, cut side up, on the baking sheet. Brush the melted ghee or olive oil all over the flesh of the squash. Season with salt and pepper. Place into oven and roast until the insides of the squash are tender and can be easily raked with a fork, about 45-50 minutes. It should have the texture of al dente pasta.
Let cool until you can handle it. Using a fork, shred the flesh into spaghetti-like strands and place into a bowl. In a large skillet with high sides, heat 2 tablespoons of ghee over medium heat. Add the garlic and cook until fragrant, about a minute. Do not let burn.
Quickly add the shredded squash to the skillet and sauté, stirring occasionally, until heated through, about 5 minutes. Add the Italian seasoning, season with salt and pepper to taste. Off heat, add the parsley and parmesan cheese, if using. Serve as a side dish or topped with your favorite pasta sauce or chili.