I've made these dozens of times and consistently these cookies are consistently large, relatively flat (but not too thin) and chewy. Here are a few things I've noted over the years.
-- The amount of egg is strange, but the end result is worth it. You could probably get away with using a jumbo size egg, but I typically have large or extra large eggs so I use an egg and an extra tablespoon.
-- Cookies made with chilled dough have a slightly better texture and bake up thicker. I like to bake a few right away, then keep the rest of the dough mounds in a heavy duty zipper bag in the refrigerator or freezer to be baked as needed. You'll probably have to increase the baking time if you are baking cookies that are chilled through and through.
-- For crispier edges, bake the cookies at 375 F. and adjust the baking time. A higher temp should give you paler centers and darker edges.
-- If you add the sugar to the butter while it is still hot, the hot butter may melt the sugar and you may get shiny cookies (this has happened to me on occasion). If you do add the sugar to the butter while it's hot, the dough will probably require some more chilling.
-- The amount of chocolate chips seems really high, but if you like chocolate you should be happy with the results. Even though the dough seems packed with chips, the cookies spread in the oven and the ratio of chips to dough seems pretty reasonable. Also, since these cookies are sweet, I use extra dark (Guittard) chips to offset the sweetness a little. Toasted nuts are always a good addition, too.
--It might be tempting to use chunks of chocolate instead of chips, but if you do that, be double sure to chill the dough. Sometimes chunks of chocolate, depending on the brand, cause more spreading than chips.