The butter is the culprit. Butter has a low melting point and goes from solid to liquid very quickly. As a result, when you put the cookies in the oven, the butter melts and the dough spreads out before the cookie can bake and set its shape.
The solution is to chill the mixed dough in the fridge for an hour or so. then put the dough onto cold cookie sheets and bake. The unused dough goes back into the fridge between batches. The cookie sheets go into the freezer between batches for a couple of minutes.
All this, while a pain in the xxx, keeps the butter in solid form long enough for the dough to set in a more rounded cookie.
Once you get a rhythm going, it's not bad at all.
"If you want to make an apple pie from scratch, you must first create the universe." -Carl Sagan