In a deep bowl Pour the flour mixed with baking powder, add the eggs, stirring constantly, yogurt and the oil. Mix nice to obtain a homogeneous mixture. Add finely grated or crumbled feta cheese and stir well again. With this mixture anoint sheet banitsa short side and rolled, you put in a suitable pan lightly greased with fat. So winding and 6 sheet like a snail in the tray. Put the pan on the bottom BBQ in the halogen oven for 20 minutes at 225 C, pozachervi slightly open and spread with margarine. After expire minutes remove the pan, take a large saucepan lid or another pan, cover the banitsa and turn it (this is for sure not remain raw underneath the lid is very easy) and put on another 20 minutes at 225 C to finish cooking by again sometime she smeared with margarine. Serve lightly chilled with kefir or compote.