Bring a large pot of lightly salted water to a boil. Cook the bow-tie pasta at a boil, stirring occasionally, until cooked through yet firm to the bite, about 12 minutes; drain and return pasta to pot. Melt cream cheese into the pasta. Stir pasta sauce, Italian seasoning, and red pepper flakes into the pasta mixture.
Heat a skillet over medium heat. Break ground beef into small pieces and add to the skillet; cook and stir until some of the fat has rendered, 2 to 3 minutes. Add onion and garlic to the beef, continue cooking until the ground beef is completely browned, about 5 minutes more. Stir beef mixture into the pasta mixture.
Pour pasta-and-beef mixture into a 3-quart casserole dish. Sprinkle mozzarella cheese over the dish.
Bake in preheated oven until the mozzarella cheese melts, 5 to 10 minutes.
