Lastly, refrigerate your dough. No, I certainly don't refrigerate the dough for all my cookies. Sometimes, it's not necessary.
For these big, chewy cookies, you will need to refrigerate the dough. It keeps the cookie from spreading out before it starts baking. You don't want a thin cookie here.
Take the cookies out of the oven while they still look fudgy in the middle. Don't worry about it at all. The heat of the cookie and baking sheet will cook it further. You can experiment with just a couple of cookies first to get the perfect bake time for your oven.