Brown the ground beef in a skillet over medium heat, breaking it into crumbles. Cook until no pink remains, then drain excess fat.

Transfer the cooked beef to the slow cooker. Add the pasta sauce and cubed cream cheese, stir, and cover. Cook on low for 2 to 3 hours, stirring once or twice, until the cheese melts into the sauce.

Near the end of the slow cooker time, boil the penne in salted water until just shy of al dente. Drain well.

Stir the drained penne into the slow cooker. Cover and cook on low for 20 to 30 minutes more, until heated through and coated in sauce. Serve hot.