Sauté spring onion in butter. Add the flour and stir continuously. Add the milk little by little. Once a medium thick sauce has formed add all the other ingredients except the filo pastry. Mix well.
Take one sheet of filo pastry and brush lightly with melted butter. Fold the pastry double length wise and brush with melted butter again. Cut pastry in half length wise. Place a rounded teaspoon of the mixture on the bottom left hand corner. Fold into a triangle and continue folding up until the pastry ends.
Bake at 200°C for 15 to 20 minutes until golden brown.