Mix the flour with the baking powder, the almond flour and a pinch of salt. Beat the eggs with the sugar to obtain a light, airy texture. Add the oil and the yoghurt. Fold in the flour mixture. Pour the batter into a floured cake pan. Line with apple slices. Bake the cake for 45 min. in a pre-heated oven (180°C). Remove the cake from the oven and set aside to cool. Brush the cake with the jam.