Peel and grate apples. Drizzle with lemon juice and let stand for about 10 minutes. Then squeeze out with your hands and mix with sugar and crumbled speculoos. Brush the dough with melted butter and arrange the apple mixture on the long edge. Roll up the dough and bake in a preheated oven at 180 degrees for about 30 minutes.
Take it out, cover it with a kitchen towel and let it cool down.