Bring a large pot of salted water to a boil. Add the jumbo shells and cook according to package directions until al dente. Drain and set aside.

Heat a large skillet over medium. Add the ground beef and break it up with a spoon. Cook until no pink remains. Drain excess fat from the pan.

Add the canned diced tomatoes with their juices to the beef. Stir in the garlic powder, onion powder, and a pinch of salt and pepper. Let the mixture simmer gently for 3 to 5 minutes to meld flavors.

Reduce the heat to low and stir in the cream or milk. Add the shredded cheddar a handful at a time and stir until fully melted and the sauce is smooth. Taste and adjust seasoning.

Add the cooked shells to the skillet. Toss gently until the shells are coated in the sauce and warmed through. If the sauce is too thick, add a splash of milk to loosen it.

Serve hot. Sprinkle with chopped fresh parsley if desired.