Preheat your oven to 180°C fan.
In a 9×6 baking dish, mash the bananas until smooth.
Add the oats, soy protein, mixed spice, cinnamon, baking powder, milk, grated carrot and raisins to the bananas.
Stir until everything is fully combined, then smooth the top and clean down the sides.
Bake for about 35 minutes, until golden and set in the middle.
Meanwhile, mix the yoghurt with a little honey and lemon juice to taste.
Once the baked oats are out of the oven, let them cool for 5–10 minutes so the squares hold their shape.
Spread over the yoghurt mixture and finish with the chopped walnuts.
Slice into portions.
Microwave for 1 minute to warm through or enjoy cold.
Store leftovers in an airtight container in the fridge.
