Cook the Pasta: Bring a large pan of well-salted water to the boil. Cook the pasta according to the packet instructions until just al dente. Before draining, reserve about 125ml (½ cup) of the pasta cooking water, then drain and set aside.
Brown the Beef: While the pasta cooks, heat the olive oil in a large frying pan over medium-high heat. Add the minced beef, season with salt and pepper and cook until deeply browned, breaking it up with a wooden spoon as it cooks. Drain any excess fat if necessary.
Make the Sauce: Add the onion and garlic to the beef and cook for about 5 minutes, until softened. Stir in the paprika and tomatoes, then pour in the chicken stock. Bring to a simmer and cook for 5–7 minutes, until the tomatoes have broken down and the sauce has thickened slightly.
Add the Cheese and Pasta: Reduce the heat to low and gradually stir in the cheddar until melted and smooth. Add the cooked pasta and toss until everything is well coated. If the sauce is too thick, add a splash of the reserved pasta water.
Finish and Serve: Stir through the chopped parsley and mozzarella until the cheese has just melted. Taste and adjust the seasoning, then serve immediately.