Combine oatmeal, water (or milk), banana, salt, and cinnamon (if using) in a saucepan.

Add raisins if desired to plump them up.

Bring the mixture to a simmer over medium-high heat, then reduce to medium heat.

Stir vigorously until the oats take on a creamy look and the banana is mostly beaten into them.

Cook until the desired consistency is reached or most of the liquid is absorbed.

Top with nuts, syrup, cream, and the remaining banana slices, if desired.