Heat oven to 180 degrees Celsius (~350 degrees Fahrenheit).
In a greased oven-safe container/baking tray (15-20x15-20), combine mashed banana, rolled oats, vanilla protein powder OR wholemeal plain flour, baking powder, honey/maple, olive oil, coffee, and milk. Mix until well combined.
Place in the oven and cook for about ~35-40 minutes, or until golden and firm to touch.
Allow oats to cool completely in the container/tray, and then loosen the edges with a knife and then combine and add the yogurt 'topping', followed by the cocoa powder, and then refrigerate.
Upon serving the next day, cut into ~4 servings. If serving warm the next day - reheat a slice in the microwave for ~1 minute (the yogurt layer actually tastes great slightly heated also, or you can add this the next day, after heating if you would prefer), or serve as is/cold.
