Fill a large pot with lightly salted water and bring to a rolling boil over high heat. Once the water is boiling, stir in the macaroni, and return to a boil. Cook the pasta uncovered, stirring occasionally, until the pasta is tender and has cooked through, about 10 minutes. Drain well in a colander set in the sink.
Cook the ground beef in a skillet over medium heat, breaking the meat up as it cooks, until the beef is browned and no longer pink. Drain excess fat. Stir in the cream cheese until melted, then mix in the mushroom soup until thoroughly combined. Stir in milk, about 1/4 cup at a time, until the mixture is the consistency of gravy. Stir in the macaroni, bring to a simmer, and serve.
