Knead the flour, butter, and baking powder. Add the yogurt and the egg, lightly beaten. Continue kneading. Leave the dough in the fridge fro 30 minutes.
In a bowl, grate the cheeses and add the mint, yogurt and the beaten eggs. Add salt and pepper and mix well.
Roll the dough into a thick pastry. Cut it into round pieces, add a spoonful of filling on each one, and close it into a crescent shape. Brush with milk to seal. Carry on until you have run out of dough.
Place the pies on a baking tin lined with parchment paper and bake at 150 °C for 20’ - 30’ until golden. serve sprinkled with a little mint or other herb.