Notice the flaky layers. I used a recipe from the always reliable Kenji Lopez-Alt on Serious Eats. His investigations and explanations are always a pleasure to read, so I'm not going to go into any of that, here. Read his.
The only thing I would add to his recipe is that you should use a cylindrical rolling pin, and not a tapered French pin (which I usually prefer). The reason is that the scallions embedded into the dough will do all sorts of crazy things as you're trying to roll the dough as thin as possible. A cylindrical rolling pin will ensure an evenly distributed pressure while you're flattening it out, and you won't have (as many) scallions poking out all over the place.