Place cranberries and chopped apple into a small saucepan. Heat over medium-high, stirring frequently to prevent scorching.
Once the cranberries begin to pop and release their juices, reduce the heat to low and continue to cook until the cranberries and apples are fully cooked down and softened. If the mixture seems dry, add water (1 Tbsp at a time) to keep some moisture in the pan.
After the cranberry-apple mixture is cooked, remove from heat and add the remaining ingredients. Add another tablespoon or two of water, if needed, to achieve desired consistency.
Taste for seasoning, adding more salt or maple syrup, if needed. Serve sauce at room temperature, or gently reheat and serve warm.
Serves 4 to 5. Can easily be doubled, and can be made up to three days in advance.