Cook pasta according to package directions. Meanwhile, in a small mixing bowl, beat cream cheese until smooth. Add milk; beat until smooth. Stir in spinach and oregano; set aside. In a non-stick skillet, cook beef and garlic over medium heat until meat is no longer pink; drain. Stir in the picante sauce, tomato sauce, chili powder and cumin; bring to a boil. Reduce heat; simmer, uncovered, for 5 minutes. Drain pasta; stir into meat mixture. In a 13X9X2-inch baking dish coated with non-stick cooking spray, layer half the meat mixture and all of the spinach mixture. Top with remaining meat mixture. Cover and bake at 350° for 30 minutes. Uncover; sprinkle with cheese. Bake 5 minutes longer or until cheese is melted. Sprinkle with olives and onions. Let stand for 10 minutes before serving.