Bring a large pot of water to a boil and generously season with salt (about 1 tablespoon). Cook pasta according to al dente package directions less 1 minute. Reserve 1 cup pasta water. Drain pasta without rinsing.Meanwhile in a large skillet over high medium heat add 1 tablespoon olive oil and brown the ground beef, cook until no longer pink. Turn heat down to low and add 1 teaspoon salt and ½ teaspoon black pepper. Stir in garlic, onions, chili flakes, Worcestershire sauce, tomato paste, parsley, and ½ cup pasta water. Simmer until meat is tender, about 5 to 8 minutes.Toss in pasta and 1 cup mozzarella. Top with remaining cheese and cover with lid. Garnish with parsley and serve immediately.