Heat the olive oil over medium heat. Add the ground beef, garlic powder, onion powder, and Italian seasoning. Cook the beef, breaking it up with a spatula, until browned and cooked through.
Add the Worcestershire sauce, diced tomatoes, marinara sauce, and parsley and stir to combine. Add the penne and the vegetable stock. Increase the heat to high and bring to a simmer. Lower the heat to medium, cover, and cook for 10-15 minutes or until the penne is tender, stirring frequently. While the pasta is cooking, preheat the oven to broil.
Uncover the pan and sprinkle the parmesan over the top. Place the mozzarella slices on top. Transfer the pan to the oven and broil until the cheese is melted.
Notes
Pasta: The pasta should cook in the sauce in about 15 minutes, but be sure to test it and cook it a little longer if it's not quite tender.Stir the pasta often: This helps it cook evenly and keeps it from sticking to the bottom of the pan.Mozzarella: Fresh mozzarella is nice and melty, but regular shredded mozzarella cheese works great, too.Ground beef: You can swap the beef for ground turkey, ground chicken, or Italian sausage.Broiling: Make sure your pan is oven-safe before placing it under the broiler to melt the cheese. If you don't have an oven-safe pan, skip the oven and cover the pan with a lid to melt the cheese.