Place the rolled oats with the chia seeds into a microwave safe bowl. Pour over about 1/4 cup of boiling water. Stir and allow to sit for 2 minutes.
Add the 3/4 of the milk and stir. Place into the microwave and cook for 2 minutes, keeping a close eye on it so it doesn’t overflow.
Remove from the microwave and stir through the cinnamon, half the banana, and any extra milk if you like your porridge runny. Return to the microwave for a further 1 minute.
Remove from the microwave and allow to sit to cool for 1-2 minutes. Top with sliced banana, maple syrup and any remaining milk.