Preheat oven to 220 degrees celsius (200 if using fan-forced).
Line two trays with baking paper and set aside.
Place the defrosted spinach into a sieve and strain out any remaining liquid.
Use paper towel to remove any remaining moisture from the spinach.
Place the spinach, feta and parmesan cheese into a bowl and mix to combine.
Spread the mixture evenly over the defrosted pastry sheets.
Roll the pastry tightly.
Use a sharp knife to cut the pastry rolls into 12 slices.
Lay the slices (cut side up) onto the baking trays).
Brush with the lightly whisked egg and sprinkle over the sesame seeds or poppy seeds.
Bake for 15 minutes or until lightly golden and crispy.