Put the dough ingredients into a stand mixer or food processor and mix until a uniform elastic dough is formed (5 minutes in the mixer)
Place the dough in an oiled bowl and set aside in a warm location for 30 minutes to rise. Cover with a teatowel. It's ready when it has doubled in size.
Cut the dough into 8 (for large pides) or 16 (for lunchbox size) equal portions.
Roll into balls (don't knock them back too much).
Place them on a floured chopping board and cover with a damp teatowel. Rise for 20 minutes more.
Preheat oven to 200 degrees celsius.
In a medium sized fry pan over medium heat, cook the leeks until soft, with a little olive oil.
Combine the leek, cheeses, spinach and egg in a bowl and mix well.
Flatten the dough balls to make an oval, then roll out flat with a rolling pin.
Fold in the sides with your fingers to make a ridge and pinch the tops together.
Put them on a lined baking tray and top with the cheese mixture.
Bake at 200 degrees celsius for 20 minutes.
Remove from the oven and transfer to wire racks to cool.
Notes
Freezer friendly, freeze flat on trays and then transfer to containers. Put in the lunchbox frozen, or defrost in the fridge overnight. Can also be reheated for at home lunches in a sandwich press.