One note that I always try to include in cookie recipes has to do with even slight variations between oven temperatures. It's practically impossible to write a standard baking time into a chewy cookie recipe. The difference between a chewy cookie and an overbaked cookie can be as little as a minute in many ovens, so I always suggest
1) getting the oven well preheated
2) get the cookie sheet into the oven as fast as possible so the heat will come back up quickly
3) with any new cookie recipe bake a test batch of only 2 or 3 cookies to get the oven timing perfect before baking the rest of the batch.
4) be sure to make a note on the recipe of the exact time that they were in the oven for when you bake the cookies next time.