My cats, Grendel & Elroy, LOVE iceberg lettuce, and cilantro. But they are not fans of Italian parsley. Weirdos!
But I do have a recipe for cat or dog treats (just make smaller balls for cats). Mix baby food (normally meat but perhaps veggie...just NO ONIONS) with wheat germ and powdered milk to form a dough, roll into balls and bake until slightly browned. My dog loves them. My cats, not so much, but as I mentioned, they are weirdos who eat cilantro!