Pre-heat the oven to 350°. Mash up the bananas or process in a food processor until smooth. In a separate bowl mix the ground flax seeds and warm water and let sit for a few minutes until it gels.
Add remaining ingredients to food processor or mix together in a bowl, make sure to add the gelled flax and water.
In a double boiler, melt the coconut oil and add the cacao and sweetener until well blended. Turn off the heat.
Pour the banana mixture into a 5x9 inch loaf pan. Use a silicone spatula to smooth it out evenly. Carefully drizzle the chocolate mixture like in the photo above. Then use a butter knife or skewer to drag up and down to create a design in the cake.
Put the cake in the oven and bake for 25-35 minutes. Remember this is a gooey moist cake, since there are no eggs, the center will be a bit gooey while the top will be more crispy.