Preheat the oven to 180°C and line a muffin tray with paper cups. Put butter in a bowl, add sugar, eggs, yogurt and vanilla essence and beat thoroughly. Stir in the sifted mixture of both types of flour, baking powder and salt. Divide the dough into paper cups (fill them to about 2/3 of the volume). Place sliced fruit on top (always at least 2 apricot slices and 2 peach slices). Place in the oven and bake for about 25-30 minutes until golden. Allow to cool and dust with powdered sugar before serving.