Remove the skin from the apples, core them, cut them into quarters and soften them with sugar, 100 ml of water and the juice of one lemon for about 10 minutes. Then whisk the apples to a puree and freeze in the freezer.
In between, beat again with the whisk until fluffy. Fill into well precooled glasses, pour 1 tablespoon of Calvados over each, garnish with apple slices and serve on the spot.