Combine the apples, sugar, ½ cup apple cider (or water), and lemon juice in a medium saucepan.
Remove the pan from the water and pour the cooled apple mixture into a large mixing bowl.
Cover, and refrigerate for at least 2 hours.
Store the mousse in the refrigerator for up to 5 days. If you serve the mousse in apples, I suggest you hollow them out and spoon in the mousse just before serving. Or, brush the inside of the apples with lemon juice or a lemon-lime soda to keep them from browning.
Apple Mousse https://hungryhappenings.com/apple-mousse/