Mix oats, chia seeds, buckwheat, dates and milk and pop in the fridge overnight. You could also add a ½ teaspoon of ground cinnamon if you fancy.
By morning the mixture will be thick, creamy and have absorbed most of the milk. Mash the banana and add to the mixture, along with a splash more milk to loosen the mixture if necessary.
Add your choice of toppings and a drizzle of maple syrup.