For the apple casserole, cut out the core and stems from the apples. Preheat oven to 200° C. Mix raisins, hazelnuts, whipped cream and honey in a bowl. Grease a gratin dish with butter. Place apples in the dish and fill with the nut mixture. Bake on the middle shelf for 20 minutes.
For the chocolate sauce, heat the milk. Mix the cornflour with a little cold milk and add while stirring. Whisk together the sugar and cocoa powder and stir into the sauce. Stir the chocolate sauce in a cold water bath.
Cut the apple casserole into portions and serve with an ice cream scoop and chocolate sauce.