Combine oats, oat flour, walnuts, cinnamon and baking powder in a bowl.
Add wet ingredients : yoghurt, eggs, carrot, mashed bananas, honey, milk & stir to combine. (Batter should be quite thick and smooth)
Divide mix into 9 muffin cases. Top each muffin with a sprinkle of walnuts (optional)
Bake for 30 minutes at 180 degress C until golden.
For the icing: Combine the full fat greek yoghurt, maple syrup and cinnamon and mix until smooth. Lather on top of each muffin like icing. Make sure the muffins are fully cooled when you are icing them.