In a small mixing bowl, stir together the flaxseed meal and water. Set aside for 5 minutes to allow the mixture to turn into a thick gel.

In a separate bowl, whisk together the flours, starch, cinnamon, baking powder, baking soda, and salt, and set aside.

Beat together the coconut oil and coconut sugar until creamy in either a stand mixer or with an electric hand mixer. Add the flaxseed gel and vanilla, and beat until smooth.

Add the flour mixture into the wet ingredients in three additions, mixing fully between each. Cover the bowl and let chill in the refrigerator for 1-2 hours.

With 15 minutes left to chill in the fridge, preheat the oven to 350ºF and line a baking sheet with parchment paper. Remove the dough from the fridge and let sit for 5 minutes. Scoop out 2 tablespoons of dough and shape into a ball. Roll in the cinnamon sugar, if desired, and place on the baking sheet. Repeat with remaining dough. For a thicker cookie, leave the balls rounded, but for a thinner cookie, gently flatten them between your palms.

Bake for 9-11 minutes, until the edges are brown and crispy. Let cool on the pan for 5 minutes, then transfer to a wire rack to cool completely.