Preheat the oven to 180c.
Tip the muesli mix into a baking dish, lined with baking paper. Sprinkle over cocoa nibs if using. Lay another piece of baking paper on top and press the mixture tightly into the dish. Remove top layer before baking.
Store wrapped in baking paper in a sealed container. Muesli bars will last for up to a week, and unused bars can be frozen for up to a month.