Preheat the oven to 400 degrees F. Halve and seed the spaghetti squash; roast, then scrape into strands (see Cook's Note).
Meanwhile, cook the pancetta in a large skillet over medium heat, stirring occasionally, until crisp, about 6 minutes. Transfer to a paper towel-lined plate using a slotted spoon; set aside. Add the shallot and thyme to the skillet and cook until softened, about 2 minutes. Stir in the wine and cook, scraping up any browned bits, until mostly evaporated, about 1 minute. Add the heavy cream, nutmeg, 1/2 teaspoon salt and a few grinds of pepper.
Increase the heat to medium high and cook, stirring occasionally, until the sauce is slightly thickened, about 3 minutes. Stir in the peas and parmesan. Continue cooking until the sauce is thick and creamy, about 1 more minute. Remove from the heat.
Add the squash and pancetta to the sauce. Return to medium heat and cook, stirring, until combined, about 1 minute. Season with salt and pepper and sprinkle with the parsley.
Photograph by Johnny Miller
How to Roast Spaghetti Squash Trim both ends with a chef's knife, then position the squash upright and halve lengthwise. Scoop out the seeds with a spoon and discard. Place the squash halves cut-side down on a baking sheet. Roast at 400 degrees F until tender, 25 minutes; let cool slightly, Scrape the squash into strands with a fork. Discard the skin.
Courtesy of Food Network Magazine