Finely chopped Italian flat leaf parsley, for garnish
Instructions
Preheat the oven to 400F.
Using a large, sharp knife, cut the spaghetti squash in half. Scrape out the seeds using a spoon and sprinkle the cut sides with olive oil. Place the squash cut side down on a baking sheet and roast until tender and easily pierced with a knife, about 30 to 45 minutes depending on the size of the squash (check at 30 minutes regardless). When the squash is done, use a fork to carefully scrape out the flesh of each half into “noodles”, taking care to keep the squash shell intact. Place the noodles in a colander or strainer and drain for 10 minutes to remove the extra moisture. Save the squash shells for serving.
In a medium saucepan, heat the butter over medium-low heat until melted. Add the cornstarch and stir until smooth. Over medium heat, cook until the mixture turns a light, golden sandy color, about 2 to 3 minutes.
Meanwhile, heat the milk until hot (microwave in a glass measuring cup, or heat in another pan on the stove). Gradually add the hot milk to the butter mixture, whisking continuously until very smooth. The first addition of milk will cause the mixture to become chunky, keep whisking and adding milk until it becomes smooth. Bring to a boil and cook 3 to 5 minutes until very thick, whisking frequently. Remove from the heat and stir in 1 teaspoon kosher salt, nutmeg and several grinds black pepper. Stir in 1 1/3 cups cheese until it melts, then add the white wine vinegar and remove from the heat.
Add the drained squash into the pan, then mix it with the cheese sauce and 1/2 teaspoon kosher salt. Taste and add additional salt if desired depending on the size of the squash. Pour the mixture back into the squash shells, dividing the mixture equally among the shells. Sprinkle each squash with the remaining cheese, then with a dusting of paprika. Bake until cheese melts, about 10 minutes.
To serve, sprinkle with chopped parsley and serve warm.