How to make
Cut the phyllo pastry sheets into small squares. Smear each sheet with melted butter and arrange them in a muffin tray, after you've smeared each muffin holder with butter.
Make a stuffing from the egg and crumbled feta cheese. Add the yoghurt with baking soda and flour and stir.
Fill each muffin holder with 1 tbsp of the stuffing. Smear the edges with beaten egg yolk. Bake in a moderate oven until golden.