1Heat oven to 350°F. Spray 8 regular-size muffin cups with cooking spray.
2In medium bowl, mix meatloaves ingredients. Scoop generous 1/3 cup meat mixture into each muffin cup, pressing down slightly.
3Bake 30 to 35 minutes or until meat thermometer inserted in center of one loaf reads 160ºF. Let stand in pan 5 minutes.
4Meanwhile, in small bowl, mix tzatziki sauce ingredients; refrigerate until serving time. Serve meatloaves with tzatziki sauce.