Preheat oven to 375°. Roll out bread with a rolling pin until flattened to about 1/16 of an inch. Stir together apples and cranberries. Brush some of the butter on the edges of the bread. Mound one half of the dried fruit mixture just right of center in the middle of each piece of bread. Fold over the bread to form a triangle and enclose the filling. Pinch the edges of the bread together firmly to seal. Arrange in one layer on a small baking sheet and brush the top of each turnover with the remaining butter. Bake the turnovers in the middle of the oven for 20 to 25 minutes or until pale golden. Top each turnover with a spoonful of vanilla yogurt, if desired.