Heat oven to 350 degrees. Spray rectangular baking dish, 13x9x2 inches, with nonstick cooking spray. Cook ground beef, onion, and garlic in 12-inch nonstick skillet over medium heat, stirring occasionally, until beef is brown and onion is tender; drain. Stir in remaining ingredients except water, flour, and potatoes, breaking up tomatoes. Heat to boiling; reduce heat. Simmer uncovered 15 minutes, stirring occasionally.

Shake water and flour in tightly covered container; stir into beef mixture. Spoon beef mixture into baking dish. Spoon potatoes evenly over beef mixture; spread to edges of dish. Bake uncovered about 30 minutes or until heated through. Let stand 5 minutes before serving.