Mix turkey, tomatoes, parsley, garlic and 1/2 cup cheese just until blended; shape into 12 (1/2-inch thick) patties. Place on baking sheet sprayed with cooking spray.
Bake 8 to 10 min. or until done (165ºF). Meanwhile, combine remaining cheese and tzatziki; spread onto cut sides of buns.
Fill buns with burgers, spinach and peppers.