Oatmeal made with water instead of milk, sweetened naturally with apple and cinnamon. The lowest calorie version of oatmeal that still tastes like something you'd want to eat.
Peel, core, and dice the apple into 1/2-inch cubes for even softening in the oatmeal.
In a medium saucepan, bring 2.5 cups water to a gentle boil over medium-high heat. Add a pinch of salt.
When the water is boiling, stir in the oats, reduce heat to low, and simmer uncovered. Stir occasionally to prevent sticking.
After 3 minutes, add diced apple and continue to simmer for another 5–7 minutes until oats are creamy and apples have softened but retain some bite.
Stir in the ground cinnamon at the very end, cook for 30 seconds more, then remove from heat. Let stand 2 minutes to thicken before serving.