Prepare the stuffing, by beating the eggs and adding the crumbled feta cheese, yoghurt and baking powder.
Spray each phyllo pastry sheet (packet of 17.5 oz (500 g)) with oil. Fold in two, add some of the filling with the feta cheese, sausage slices and form pies.
Arrange in an oven dish onto baking paper. Add 1 cup of milk.
Add pieces of butter and bake in a preheated 356°F (180 °C) oven until ready.