Preheat oven to 400 and line a baking sheet with parchment paper.
Place marshmallows on prepared sheet. Bake in oven until puffed and browned, about 2-3 minutes. (Keep a close eye on the marshmallows given they can burn easily.)
In a blender, combine banana, cauliflower, yogurt, cocoa powder, toasted marshmallows, one of the graham cracker sheets and almond milk. Blend until smooth or desired consistency.
Pour smoothie in glass and crumble remaining graham cracker sheet on top.