Pies consist of a round pastry base, usually 27 to 32 centimetres in diameter, which is flat with raised edges. Pies are essentially different from tarts as the base is made of a different type of dough, usually a sweet yeast dough, sometimes also lentil or sponge dough. Traditional (fermented) flan dough resembles bread dough and is usually somewhat heavier than pie dough. Kneading the dough (nowadays mostly by machine) can be quite laborious. After rising, the dough base is placed in a special baking tin. This is usually a filling of (uncooked) fruit, such as gooseberries, cherries, plums, apples or apricots, but also a filling of compote, apple sauce, pudding or rice pudding is possible. The filling is sometimes covered with a layer of puff pastry ('toeslag'), a layer of dough crumbs ('kruimelvlaai') or a grid of dough ('ruitjes-', 'riempjes-' or 'ladderflaai'). The pie is baked together with the filling on an iron baking sheet in a hot oven. After baking (and cooling) cinnamon, icing sugar or whipped cream is sometimes added.