Put the bananas, eggs, oil, cinnamon and milk in a blender. Pulse for a few seconds, until you get a smooth paste. Add the nuts and oast and pulse again until you get a textured batter.
Add the flour and baking powder, then then pulse for a few more seconds, until the batter is combined. Add more oat milk, if needed – you should have a thick, but pourable batter.
Heat the waffle maker. Once it’s hot, spoon in some batter, then seal.
Following the machine instructions, cook the waffle for about 5 minutes - it should be golden brown and crispy. Transfer to a plate and make more waffles using up the batter. You should be able to make 3 or 4 waffles, depending on the size of your machine.
Serve the waffles with banana slices, hazelnut and maple syrup or with hazelnut spread such as Nutella.