1. In a medium saucepan, melt 1 tablespoon butter over medium heat. Cook 1 chopped peeled apple with a pinch of nutmeg until apple begins to soften, about 3 minutes.
2. Add 1 cup cranberries, 1 cup apple cider, and 1/2 cup sugar; bring to a boil. Reduce heat; simmer until apple is tender and sauce is thick, 10 to 15 minutes. Remove from heat; stir in 1 tablespoon butter. Purée in a blender until smooth. If too thick to pour, stir in up to 1/2 cup more apple cider. Store, covered, in the refrigerator up to 1 week or the freezer up to 3 months.