Choose a new cookbook worth up to £28 when you subscribe to our magazine.
Heat oven to 190C/170C fan/gas 5. Mash up one banana half, then mix it with the oats, cinnamon, milk, 300ml water and a pinch of salt, and pour into a baking dish. Top with the remaining banana halves and scatter over the walnuts.
Bake for 20-25 mins until the oats are creamy and have absorbed most of the liquid.