Method Prep:45min › Cook:30min › Extra time:4hr › Ready in:5hr15min
Make the starter
Dissolve the yeast in the water with sugar and let stand until foamy. Place the 100g flour in a bowl and add the yeast. Mix and knead for a few minutes, then place in an oiled bowl, cover with a damp cloth and let stand for 1 hour in a warm place (like the cold oven with the light on).
Make the dough
Add to the starter 400g of flour, eggs, oil, salt and 200ml water or as needed to make a sticky but soft dough. Knead on a floured surface for 5 to 7 minutes, then cover with a damp cloth and let rise for 2 hours or until doubled.
Make the filling
Combine ham, mozzarella, ricotta and grated Parmesan in a bowl. Stir to make a not too runny mixture (or it will wet and pierce the dough). If ricotta is too soft or wet, let drain a few minutes before adding to the mixture.
Fill and bake
Transfer the dough to a floured surface and make a 4-5cm thick log. Slice the log in 30 small pieces and roll each into a 4-5cm circle.
Fill each circle with 1 heaped teaspoon of filling.
Fold the sides towards the centre, sealing the filling.
Roll the dough between your palms and make a ball. Transfer to a baking tray lined with parchment. Proceed the same way making 30 balls and placing one close to the other without touching.
Cover with a damp cloth and let rise for 1 hour. The balls of dough will rise and touch one another.
Preheat the oven to 200 C / Gas 6.
Brush the balls with the beaten egg, then transfer to the preheated oven. Bake for 30 minutes or until the rolls are golden and well risen. Remove from oven, cool and serve. Store in an airtight container up to 48 hours.