Bring water to a boil in large pot for pasta. When the water boils wait until meatballs go into oven. When meatballs have been in oven 4 to 5 minutes, season water with salt, add spaghetti and cook to al dente. Drain pasta and keep warm.
Soak stuffing with about 1 cup stock in small bowl until softened, a couple of minutes.
Place turkey in mixing bowl and season with salt and pepper. Add apple, lemon juice, celery, onion, poultry seasoning, egg and stuffing and mix until just combined. Line a baking sheet with parchment paper. Form meat mixture into 16 (2-inch) balls, drizzle with some olive oil and roast until cooked through, firm and golden, about 12 minutes.
While meatballs roast, heat a couple of tablespoons olive oil in large skillet, add mushrooms and thyme and cook over medium-high heat until tender and season with salt and pepper. Make a well in the center of the pan, add the butter, and when melted, whisk in the flour. Cook for 1 minute then whisk in about 2 cups stock and Worcestershire sauce. Reduce heat to low and cook for a few minutes to thicken the sauce, then stir in cream.
Toss pasta in a large serving bowl with the meatballs, sauce and cheese. Garnish with parsley and serve.