Into a blender, add oats, milk, mashed banana, maple syrup, cinnamon, baking powder and salt and blend until smooth.
Pour half of the batter into a ramekin. Add some peanut butter in the middle, and cover the peanut butter with the remaining batter.
Bake in the middle of the oven for 20-30 minutes. I usually do 25 minutes.
Enjoy!
Notes
If you want to save some time, try air frying the oats instead at 170C/338F for about 15 minutes, and you should end up with the same result taste wise.