Combine the oats, water, apples, walnuts, cranberries, salt, and cinnamon in a medium-size saucepan. Bring to a boil over medium-high heat, stirring occasionally.
As soon as it boils, reduce heat to low and simmer for just a few minutes, until the oats are soft and the apples are tender. Remove from the heat.
Scoop into bowls and top with butter and the sweetener of your choice, if desired.
Notes
Pecans may be substituted for the walnuts in this recipe. Alternatively, the nuts may be skipped entirely if they aren't your thing.