Preheat the oven to 350F and line a baking sheet with parchment paper or a silpat. Pour 1.5 cups of oats into a blender or food processor, and process them into a fine flour.
In a large bowl combine the ground flax seeds with the water, and stir well to mix. Let sit for 5-10 minutes. Add in the coconut oil, coconut sugar, debittered brewer’s yeast, vanilla, baking soda, and salt, and stir again until well combined.
Drop the dough by heaping tablespoons onto the lined baking sheet, then use your fingers or a back of the spoon to flatten the cookies. Leave a little room between the cookies to allow for spread.
Bake at 350F for 10-12 minutes, until the cookies are lightly golden around the edges. At 10 minutes your cookies will be crisp around the edges but nice and soft in the center.