Preheat the oven to 350°F. Grease and line an 8x8 baking pan with parchment and set aside.
Whisk together the flaxseed meal and water in a small bowl. Set aside for 5 minutes.
Meanwhile, blend the chickpeas, banana and almond butter in a food processor until completely smooth. Add flax egg and blend again.
Add remaining ingredients (minus hemp seeds) and blend until a dough forms. Pulse in hemp hearts.
Dump the batter into the prepared pan. Bake on the center rack for 22 - 26 minutes until a toothpick inserted into the center comes out clean.
Let cool in the pan for 10 - 15 minutes, then transfer to a wire rack and cool completely before frosting and slicing.
While the brownies are cooling, prepare the icing. Melt the coconut butter and coconut oil together in a small saucepan. Whisk in maple syrup until combined (the mixture should get very thick). Slowly whisk in almond milk until mixture has become smooth. Whisk in peppermint extract. Remove from the heat and transfer to a mixing bowl. Whisk in remaining ingredients and allow icing to cool until brownies have cooled completely.
Spread icing over brownies, sprinkle with crushed peppermint candies if using, and slice into 12 - 16 bars. Store in an airtight container for 2 - 3 days.