Preheat oven to 170 °C / 340 °F top and bottom heat.
Line a baking tray with baking paper.
Add bananas, rolled oats and oil into a high-speed blender or food processor and process into a sticky dough.
100 g overripe bananas, 100 g rolled oats, 25 g rapeseed oil
Pour the chopped hazelnuts onto a plate or flat surface.
60 g chopped hazelnuts
Take some dough using a teaspoon and shape a coarse ball of approx. 2 cm / ¾ inch. Roll it in the hazelnuts until entirely wrapped and shape a nice ball using your hands. Place the ball on the prepared tray.
Place the balls in the oven for 5 minutes and then set aside to cool.
Chocolate Coating
Combine melted chocolate with oil.
75 g dark chocolate, 5 g rapeseed oil
Place a truffle grid or a fine-meshed cooling rack above a bowl to catch the excess chocolate.
Put the balls onto the truffle grid and pour over the chocolate until entirely coated.
Place in the refrigerator and let set for around an hour or overnight.