In a large pot of boiling salted water, cook pasta to al dente. Drain and set aside.
In a large skillet over medium heat, brown the ground beef. Season with garlic salt. Drain fat, if needed. Stir in marinara sauce and let simmer 10 minutes.
In a medium bowl, combine sour cream, cream cheese, and onion and mix well.
In a 9×13-inch baking dish, arrange half of the noodles, followed by the meat mixture, followed by the sour cream mixture, and finally by the remaining noodles.
