Yes, you can use baby spinach to make this recipe, but just because you can doesn't mean you should. Baby spinach is very fragile and doesn't hold up well to the type of blanching and seasoning in this recipe. However, if you have no other spinach options, use baby spinach with the understanding that it may break apart more easily while tossing with the seasoning ingredients. It will also not last as long as leftovers in the refrigerator (maybe one day).