Preheat oven to 350 degrees Fahrenheit. Prepare flax egg, set aside. Line cookie sheet with parchment paper.
In a large bowl, whisk tahini, maple syrup, and flax egg together. Add almond flour, coconut sugar, baking powder, baking soda, salt, and vanilla extract. Stir to combine.
Chill dough in refrigerator for 45 minutes.
Using a tablespoon, scoop cookie dough and gently roll into a loose ball with your hands. The dough will be sticky, so spray your hands with cooking spray as needed to make rolling easier. Place on cookie sheet, press a chocolate piece in middle if using.
Bake for 10-12 minutes or until cookies start to look golden on top. Allow to rest on cookie sheet for 2-3 minutes before removing with a spatula and placing on wire rack. Leave on wire rack until completely cool.
Store cookies in an airtight container. If stacking, layer pieces of parchment between to avoid cookies sticking together.