In a large bowl, mix together the oats, flax seed meal, and oat bran.
In a small saucepan, whisk together the cocoa powder, coconut oil, agave (or honey) and chopped chocolate. Drizzle over dry ingredients and fold until combined.
Spread out on a greased baking tray and bake for 30-45 minutes, stirring every 10 minutes.
Remove from oven and sprinkle the marshmallows, extra chopped chocolate, and cacao nibs while still warm. Let cool completely before storing.