Preheat the oven to 350°F. Line 2 baking sheets with parchment paper and set aside.
In a small bowl, whisk together the flax meal and non-dairy milk. Set aside to thicken, about 5 minutes.
In a medium mixing bowl, whisk together the flour, cocoa powder, sugar, baking powder, baking soda, salt, and instant coffee granules, if using.
In a large mixing bowl, whisk together the melted coconut oil, vanilla, and flax and milk mixture.
Stir the dry ingredients into the wet ingredients. Make sure to scrape the bottom of the bowl to fully incorporate all the ingredients. Once the dough gets thick, I find it easiest to use clean hands to form a ball of dough. The dough should be thick and moist, but not sticky or crumbly.
Using 1 ½ tablespoons of dough at a time, roll into a ball and place on a large plate. Repeat with the remaining dough until gone. A cookie scoop will help with uniform sizing among all the cookies.
Place the powdered sugar into a bowl and roll the dough balls in the sugar, a few at a time, until fully coated. Place them onto the prepared cookie sheets about 2 inches apart.
Bake for 9 to 11 minutes until the cookies have spread and the tops have that classic crackle look.
Let cool on the cookie sheet for about 1 minute before transferring to a wire rack to cool completely.