To toast the walnuts, heat walnuts in a dry, heavy but small skillet over medium heat for 1 to 2 minutes or until golden brown. You must stir constantly to ensure even toasting and prevent burning.
Remove the walnuts from the pan and set aside to cool in a plate or bowl.
To make the oatmeal, add the water, milk and mashed banana to a saucepan.
Bring to a boil over medium heat, and then add the oats and spices.
Cook the oats for 3-5 minutes while stirring occasionally. It will be a little soupy but that’s ok. It will firm up as it cools.
Add the brown sugar, if using, and then stir to combine. You could also add the brown sugar as a topping when you are ready to serve.
Divide the oatmeal into two serving bowls.
Top with the remaining banana and walnuts, if using.
Serve hot with a drizzle of milk and an extra sprinkle of brown sugar.