In a medium bowl, add all ingredients: peanut butter, flax egg, coconut sugar, baking soda and optionally, vanilla and salt. Using a rubber spatula, thoroughly stir and fold until well mixed.
Using a medium cookie scoop, scoop and drop cookie dough balls onto the prepared baking sheet, spaced evenly apart. Using a fork, press down on cookie to flatten. Repeat in the opposite direction, creating crisscross marks. Cookie won’t spread much.
Bake for 10-14 minutes. Mine took 12 minutes. Transfer cookie sheet to cooling rack, and allow to cool for 20-30 minutes—do not remove from sheet for at least 20 minutes, as cookies are very soft and fragile. Then, if desired, transfer cookies directly onto the cooling rack to cool until completely cooled. After cooling, cookies will be firmer, but a tad fragile and melt-in-your-mouth. Handle with care. Enjoy! Storing notes below.