Fill a large stockpot ¾ full of water, cover, and bring to a boil. Add 2 teaspoons of the salt and the spaghetti and cook until al dente, 8 to 10 minutes. Drain, rinse under cold water, and set aside.
Preheat the oven to 375°F. Butter a 9×13-inch baking pan.
In a medium sauté pan or skillet, melt the butter over a medium heat. Add the flour and cook, stirring, until faintly colored, about 2 minutes. Gradually whisk in the stock or broth until the sauce is smooth and thickened, 3 to 5 minutes.
Whisk in the cream, then add the remaining ½ teaspoon salt, the rosemary, thyme, nutmeg, and pepper. Stir in the turkey and peas and heat through. Taste and adjust the seasonings, then remove from the heat.
Put pasta in the prepared dish and spoon the turkey mixture over it.
In a small bowl, combine the bread crumbs and the Parmesan. Sprinkle evenly over the sauce.
