Step 1. Pre-heat the oven to 200C (fan forced). Boil the kettle in preparation for blanching the silverbeet & lightly oil 2 small pie dishes.
Step 2. To prepare the silverbeet, remove the stems and wash. Place the silverbeet in a bowl and pour over enough boiling water to cover the silverbeet. Blanch for 20 seconds before rinsing under cold water to stop the cooking process. Drain and dry the silverbeet thoroughly before chopping finely. 
Step 3. In a large bowl add all of the ingredients up until the filo pastry, reserving 1 egg for the egg wash. 
Step 4. To assemble, lay two sheets of filo side by side - the longest side of the filo should be facing you. Brush melted butter down the middle and slightly overlap the filo to bind the sheets together. Brush the filo sheets with butter and continue layering, until you've achieved a total of 4 layers, using 8 sheets. 
Step 5. Next place half the mixture along the long side of the pastry about 2cm from the edge. Roll the pastry into a long log and shape into a coil, making sure to tuck the end underneath.  Place the pie into a pie dish. Using a pastry brush lightly brush the pie with egg wash and sprinkle over half the nigella or sesame seeds before placing into a pre-heated oven for 15-20 minutes or until golden brown. Repeat process with remaining ingredients. 
Step 6. Serve with a lemon wedge.