Preheat the oven to 180°C/fan 160°C/gas mark 4. Mix together the porridge oats, baking powder and cinnamon. Whisk in the egg and buttermilk, then the mashed bananas, until combined.
Grease a silicone 4 rectangle waffle mold with 1 tsp oil and place on to a tray. Pour in the mixture evenly, then transfer to your oven and bake for 30-35 minutes until cooked through and a little crispy on the edges.
Meanwhile, heat a medium non-stick frying over a medium heat until hot. Add the walnuts and toss in the pan for 3-4 minutes until toasted. Remove from the pan, roughly crush and set aside.
Toss the sliced banana in the maple syrup. Heat the remaining oil in the same frying pan over a low-medium heat and add the banana. Cook, turning frequently, for 5 minutes until the banana becomes golden brown and crispy on the edges. Remove from the heat and set aside.
Add the yogurt and double cream along with the vanilla paste to a small bowl and beat with an electric whisk until whipped into soft peaks. Serve the whipped yogurt with the waffles, caramelised bananas and walnuts.