Preheat the oven to 350F and line a baking sheet with parchment paper or a silpat. In the bowl of a food processor fitted with an “S” blade, process the dates and pecans together until a crumbly texture is formed. Add in the cocoa powder, salt, baking soda, vanilla, and chia or flax egg (see how to make a flax egg here) and process again until the batter is relatively smooth, a little stickier than traditional cookie dough.
Add in the chocolate chips and briefly pulse, just to combine.
Spoon the batter onto a lined baking sheet, and use your hands to gently flatten the cookie dough. These cookies don't spread much, so be sure to shape the cookies the way you'd like them to look when they're done baking. (Tip: Wet your hands with water to prevent sticking!) Bake at 350F for 12 to 15 minutes, or until the edges are firm and your house smells like brownies. Allow to cool on the pan for 10 minutes, then transfer the cookies to a wire rack to cool completely.
Serve immediately, and store the leftovers in a sealed container in the fridge or freezer for best shelf life. These cookies should last a week in the fridge, and for several months in the freezer.