Grease a rectangular baking tin and place 4-5 pastry sheets into it, grasing each one before adding the next. Add half the kaseri and half the feta with a little pepper. Add two more filo pastry sheets, then add the rest of the cheeses and pepper. Cover the pie with the rest of the filo pastry sheets (each packet contains about 10), and piece with a fork.
In a bowl, beat the eggs, mix well with the milk and empty the mixture onto the pie. Place in the fridge for 30 minutes before baking..
Bake in a preheated oven at 180° C for about 40'.