Chicken Primavera Spaghetti Squash Boats

Preheat oven to 400°. Drizzle cut sides of spaghetti squash with oil and season with salt and pepper. Place cut side down on a large, rimmed baking sheet. Roast until tender, 30 to 35 minutes. Let cool slightly. Using a fork, break up squash strands. Meanwhile, make primavera filling: In a large skillet over medium heat, heat oil. Add onion and pepper and cook until mostly tender, 3 to 4 minutes, then add tomatoes, zucchini, garlic, and lemon zest. Season with salt, pepper, and Italian seasoning and cook 3 to 4 minutes more. Stir in chicken and remove from heat.  Divide mixture between spaghetti squash halves and stir to combine. Top each spaghetti squash with cheese and return to oven to melt, 5 minutes.  Top with Parmesan and parsley to serve.