Cook the spinach, drain, and squeeze out any excess liquid.
In a large bowl, combine spinach, cheese, and egg, tomato, and season with pepper.
Place equal spoonfuls of mixture onto one half of each piece of pastry and brush edges with milk. Fold over to form a triangle and press edges together with a fork. Place onto a greased or baking paper lined tray.
Brush with milk and bake for 15 to 20 minutes or until pastry is puffed and golden.