Place cheese and onion into a bowl and add the beaten egg.
Stir well to form a thick paste.
Spread the paste evenly over the pastry, going right to the edges. Press down well.
Roll from the top edge towards you, keeping it as tight as you can without squashing the roll.
Tuck in the ends and ensure the join is well sealed. Using both hands gently keep rolling the ‘sausage’ to combine it well and slim it down to about a 30cm/12” length. Score at 1cm spaces. Chill well. By chilling for a longer time you will have a better round shape as it cuts more cleanly.
When ready to cook, cut into rounds using the score marks. Place on a baking tray leaving room for spreading.
Bake for 15 minutes until golden.
Notes
Tip: The logs may be frozen uncooked, ready for defrosting when ready and baked as above.