Mix the yogurt with sugar and lemon juice and season to taste. Wash the apples, remove the core, grate and add to the yoghurt. Stir well. Whip the cream until stiff and fold in. Chill in the refrigerator.
Melt the butter in a pan and then add the sugar, the chopped almonds and the oat flakes and roast until crispy. Let cool in a bowl.
Pour the yogurt into small bowls and sprinkle with the roasted almonds and oat flakes.