Sauté the pancetta in
Add the remaining olive oil to the skillet and heat over medium heat. Add the onion, carrots, and celery; cook, stirring occasionally, until tender, about 10 minutes.
Meanwhile, heat a large pot of salted water to boiling.
Add the garlic, tomato sauce, and pancetta to the vegetables. Season to taste with salt and pepper. Heat the sauce through and keep warm.
Add the pasta to the boiling water and cook until al dente. Drain and transfer to a pasta bowl. Add the mozzarella to the sauce and pour it over the pasta. Quickly toss to combine. Sprinkle with the parsley and Parmesan. Serve at once.