(*) for a mold of about 2 liters, should offer for 6 to 8 people.
Pre-cook and cook: about 40 min, refrigerate: at least 120 minutes.
Bring sugar with water and juice of one lemon to a boil in a wide frying pan without stirring. Reduce temperature, gently rolling the frying pan back and forth occasionally, until a light brown caramel is formed. Pull frying pan off the heat. Add butter; let melt. Mix apple rings with juice of one lemon, add to caramel form, gently billow over medium heat in about TEN min uncovered. Remove frying pan from the plate, cool apple rings.
Mascarpone mixture: whisk mascarpone in a baking bowl until smooth, add sour milk and sugar, stir well. Mix in the diced apples and leave to cool with the lid closed.
Stir in water, caramel sauce and Calvados.
Pour in: place half of the biscuits, sugared side down, on the bottom of the mold. Drizzle half of the liquid over the top, then top with half of the caramelized apple rings and spread half of the mascarpone mixture evenly on top, spreading smoothly. Dip the remaining cookies one at a time into the liquid, place on top, cover with remaining apple rings and mascarpone mixture, spread smooth. Cover and leave to cool for at least 120 minutes.