Preheat oven to 350 degrees, grease or line a cookie sheet with a baking mat or parchment.
I the bowl of the mixer, place the butter add sugars. Beat to mix well, then add in the eggs (of the flax egg) and vanilla, scraping the sides if necessary.
With the mixer on low, quickly sprinkle in the gum, salt, baking soda, and baking powder. Turn mixer off (beating too much will heat the butter up, which we do not want).
Add in the flours. Mix just until incorporated, turn off.
Add in the chocolate chips. Mix just until incorporated.
Using a about 1.5 tablespoons per cookie ( I love using a cookie scoop so the all the cookies are a uniform size and cook evenly), place each ball of dough a couple of inches apart. I can fit 12 cookies per sheet (3 x 4).
Bake in a preheated oven for 8-10 minutes. If you like crispier cookies, add a minute or 2. If cookies seem poofy, give the the cookie sheet a hard slam on the counter top to deflate them a bit...works like a charm!
Let rest a few minutes before removing to a cooling rack. Continue with the remaining dough.