preheat the oven to 350°F
line an 8x8 baking pan with parchment paper, covering all four sides of the pan
in a food processor or high speed blender, process the cashews and water until creamy, scraping the sides as needed. Make sure you end up with a very creamy paste and there are no chunks of cashews remaining.
in a bowl whisk the egg, then whisk in the cacao, flaxseed meal, honey, vanilla, baking soda and salt. Mix in the cashew butter until everything is well combined. Batter will be thick.
pour batter evenly onto the bottom of the prepared baking pan and bake until a toothpick inserted into the center comes out clean, approximately 20 minutes
set pan on a wire rack to cool then cut into squares
optional: melt about 1/4 cup dark chocolate in a double boiler and drizzle over the top of each square. I do this by using a ziplock bag and cutting a small whole on one end. Store in an airtight container at room temperature or refrigerated.