Preheat oven to 180 degrees. Mash your bananas. The riper, the better.
Mix the oats and coconut into the mashed bananas. Get in there with your hands if you feel you need to.
Roll the mixture into approx 18-20 balls and then flatten with your hand onto a baking tray with a sheet of greaseproof paper. The balls will probably be a little crumbly, but if you make sure your balls are rolled nice and compact they should flatten fine.
Pop into the oven for around 12-15 minutes, until the edges and tops start to golden.
Remove from oven. Allow to cool for a few minutes then transfer to a cooling rack for 20 minutes.
While the cookies are cooling, melt your dark chocolate by breaking it into small pieces and placing them in a heatproof bowl over a pan of boiling water.
When the cookies are cooled and the chocolate melted, take each cookie in turn and half dip it into the chocolate. Replace each cookie onto the greaseproof paper.
When all cookies are dipped, transfer them to the fridge for the chocolate to set, for around 20-30 minutes.