If you're in the mood for burgers but it's too chilly outside to grill, this cheeseburger pasta dish will hit the spot. Everything, including the pasta, cooks in one pot for a quick and easy way to get a satisfying meal on the table without a lot of clean-up.
Heat the oil in a large pot or Dutch oven over medium-high heat. Add the white and light-green parts of the scallions and cook, stirring occasionally, until softened, 2 to 3 minutes. Stir in the garlic and cook until just fragrant, about 1 minute. Add the ground beef, 1 teaspoon salt and a few grinds of black pepper and cook, breaking up the beef into small pieces, until no longer pink, 5 to 6 minutes.
Stir in the ketchup, mustard and tomato paste. Add the milk, macaroni, 2 cups water, 3/4 teaspoon salt and a few grinds of black pepper and stir to combine. Bring the mixture to a boil, then reduce to a simmer, cover and cook until the pasta has absorbed most of the liquid and is softened, 13 to 15 minutes.
Uncover (any remaining liquid will thicken as the dish sits), add the cheese and stir until melted. Garnish with the parsley and remaining scallion greens.