Ensure the spinach is thoroughly drained to prevent a watery gratin. For an extra layer of flavor, consider adding a pinch of nutmeg to the spinach mixture. Pounding the chicken breasts ensures even cooking and prevents them from drying out. If you don't have liquid aminos, tamari or soy sauce works as a suitable substitute. Garnish with a sprinkle of fresh parsley or a lemon wedge for added visual appeal.