Preheat the oven to 220 C/425 F/Gas 7.
Line 2 large baking trays with baking paper.
Weigh the Feta cheese into a large bowl first and mash it (or squish with hands) until it has become a smoothish paste.
Add the grated Mozzarella cheese and mash this into the Feta.
Mix the tapioca starch and baking powder together in a separate bowl and then add to the cheese, along with the eggs.
Mash (or hand-squish) all the ingredients together until they form an evenly-blended, sticky 'dough'.
Rub a little oil onto your hands (it also may help to wear some food-preparation gloves) and hand-roll the dough into about 26 walnut-sized balls. Arrange these on the baking trays with space between them.
Place in the pre-heated oven and bake for 5 minutes, then turn the oven down to 200 C/400 F/Gas 6 (don’t open the door).
Cook for a further 10 minutes until the rolls are risen and golden.
Remove from the oven.
Best eaten fresh and warm. Rolls can be ‘refreshed’ in the microwave on high for a few seconds only if necessary to re-warm. Freeze fresh on the day of making and warm them in the microwave.
