Slice the frozen banana into chunks if it isn't already sliced, so it blends smoothly without straining the blender.
Pour the cooled cold brew coffee and almond milk into the blender jar first, this keeps everything moving under the blades.
Add the banana chunks, cocoa powder, reishi mushroom powder, almond butter, maple syrup, and cinnamon.
Drop in the ice cubes.
Blend on high for 45 to 60 seconds until smooth and no banana chunks remain, stopping once to scrape down the sides if needed.
Taste and adjust: add more maple syrup if it's too bitter, or a splash of almond milk if it's too thick.
Pour into two glasses and serve right away.