Fry the onion in butter until soft.
Wash and dry the spinach so there is very little water and sweat with the onion for a few minutes.
Take the pan off the heat and add the soft cheese, parmesan, egg and seasoning, mixing it all together.
Take one sheet of filo and cut into 10cm wide strips. Brush on one side with the melted butter. Put a table spoon of the mixture in the top right hand corner. Fold this over to make a triangle and keep folding the triangle down the length of the strip so you end up with a triangular parcel several layers thick. Repeat until all parcels have been made.
The parcels can be frozen at this stage.
Preheat the oven to 200 degrees C / gas mark 6/ Brush the parcels with a light coating of melted butter and dip into a plate of sesame seeds. Cook the parcels in the hot oven for 10-15 minutes until golden brown.
Serve with crisp green salad.