Preheat oven to 350F and line a baking sheet with a baking mat or parchment paper. In a small bowl, mix together the ground flax seed + water for the flax egg, and set aside to thicken (at least 5 minutes).
Add the brown sugar and butter to a large bowl and using an electric mixer, beat them together until creamy. Beat in the flax egg, vanilla, baking soda and salt.
Beat in the flour, ¼ cup at a time, and then fold in the chocolate chips.
Form the dough into small balls and place on your prepared baking sheet. Flatten slightly with the palm of your hand.
Bake for 12-14 minutes. Allow to cool for at least 10 minutes before eating.
Recipe by Vegan Recipes from Cassie Howard at http://www.veganinsanity.com/recipes/vegan-chocolate-chip-cookies/