Remove the core from the peeled apples. Chop the apples into small pieces and mix with half of the rum and the granulated sugar and leave to rest for about 12 hours (preferably overnight).
The next day, roughly chop the walnuts and mix well with the other ingredients (preferably by hand). Then mix in the apples.
Shape this dough into two rolls (possibly three), spray or brush with water and bake in the oven preheated to 180 ° for about 1 hour.