Cook pasta according to al dente package directions less 1 minute. Reserve 1/2 cup pasta water. Drain pasta without rinsing.
Meanwhile in a large skillet over high heat add 1 tablespoon olive oil and brown beef while breaking up with a wooden spoon, about 2 minutes. Reduce to medium heat. Season with 1 teaspoon salt and 1/2 teaspoon black pepper. Stir in garlic, onions, chili flakes, Worcestershire sauce, tomato paste, parsley, and 1/2 cup pasta (or plain) water. Simmer until meat is tender, about 8 to 10 minutes.
Toss in pasta and 1 cup mozzarella. Top with remaining cheese and cover with lid. Garish with additional parsley.
I used leftover pasta. If you don't have any on hand, there are cooking directions in the recipe.