How to make
Melt 1/2 the butter, set the rest aside. Beat the eggs in a bowl, add the yoghurt, baking powder and milk. Crumble the feta cheese in a bowl and stir the mixture.
Take 1 phyllo pastry sheet, smear it with butter and fold in 2 lengthwise to obtain a rectangle that can fit in the tray you'll be baking. Smear your rectangular cake form with oil - its bottom and sides.
Place the folded sheet in it, smear with butter on top, fold a 2nd sheet the same way and place it atop the 1st. Sprinkle the sheets with part of the filling.
Place sheets again: smear 1 with butter, fold in 2, place atop the filling in the form, smear the top, place the next, smear, etc. Repeat for all of the sheets, putting filling after each and finishing off with filling.
Take the set aside butter, cut it into pieces and put it at the very top. Put the form in a 320°F (160 °C) oven and bake about 1 hour until ready.