Preheat oven to 350 degrees. Spray a 2 quart baking dish with nonstick cooking spray.
Cook beef, onion and 1 1/2 teaspoons of the garlic in a large skillet over medium heat, stirring fequently, until the meat is browned and crumbly. Mix in the the tomatoes, parsley, oregano, cumin, cinnamon and salt.
Spoon beef mix into the prepared dish. Arrange pita bread on top of the beef.
Bake until the filling is bubbly and pitas are golden, 20-25 minutes.
Meanwhile, combine cucumber, yogurt, mint and remaining garlic; mix well. Serve sauce with casserole.