In a large mixing bowl, combine the ground turkey, spinach, Feta cheese, 2 minced garlic cloves, egg, olive oil, salt, pepper, oregano, basil and rosemary and stir together until thoroughly mixed. Form into four equal patties and place on a platter or cutting mat. Cover with aluminum foil and refrigerate for at least one hour*.
*Once you’ve placed the turkey patties in the refrigerator, take out a smaller mixing bowl and combine the Greek yogurt, grated cucumber, remaining minced garlic clove, lemon juice and dill, stirring until thoroughly mixed. Cover and refrigerate for at least one hour so that the flavors meld together.
When ready to cook, lightly mist a nonstick grill pan or skillet with cooking spray and bring over medium heat. Place the burger patties on the pan (you may need to work in batches depending on the size of your pan), and cook for 5 minutes. Flip the patties and cook for an additional 5 minutes until the burgers are cooked through.
To build each burger, place a couple leaves of lettuce on the bottom half of a burger bun and top with two slices of tomato. Add the cooked burger patty and top with 2 ½ tablespoons of tzatziki sauce (from step 2) followed by the top of the burger bun. Dig in!