Add apple cider, sweet potatoes and ginger to a medium sized saucepan. Cover and cook at a simmer for 25-30 minutes until sweet potatoes are very tender.
Remove pan from heat and blend until smooth with a stick blender or transfer to blender. Return to heat and stir in nutmeg and molasses.
Cook an additional 15 minutes uncovered at a low simmer. Stir frequently until mixture resembles a thick paste and sticks to a spoon when inverted. Remove from heat, let cool to room temperature and transfer to a lidded glass container. Can be stored in the refrigerator up to one month.