First make the pizza dough. Mix together the yeast and sugar with 325ml warm water and leave for a couple of minutes. Meanwhile, sift the flour into a mixing bowl, add the salt and make a well in the middle. Pour the oil into the well, followed by the yeast mix. Using a spoon, bring the flour into the middle from the sides, mixing slowly, bit by bit, until a dough begins to form. Once you reach this stage, work the rest together with your hands.
When combined, tip the dough onto a floured work surface and knead for 10 minutes until smooth. Clean out your mixing bowl, dust it with flour and put the dough back into the bowl. Cover with a tea towel and leave to rise in a warm place for about 1 hour until doubled in size.
When the dough is risen punch out the air and tip onto a floured work surface. Knead the dough for 1–2 minutes to push out any excess air, then wrap in cling film and chill if not using immediately.
When you’re ready to make the pizzas, divide the dough into 4 equal balls and keep them covered. Put a large (26cm) grillproof frying pan on the heat (you can cook 2 bases at a time if you have 2 pans) and roll out one ball of dough on a floured work surface with a floured rolling pin until it’s the same size as your pan. Pour a little olive oil into the pan and add the pizza base, pressing it down. Cook over a medium heat for 5–8 minutes until the base crisps and the dough starts to cook through and bubble up.
Spread 2 tablespoons of the passata over the pizza base. Tear the mozzarella balls in half, then tear one half into 4 pieces and dot them over the base. Season with pepper and scatter over a few rosemary leaves. Remove from the pan and set aside. Repeat with the remaining pizzas. (If you want to try the alternative toppings, build them up in a similar way.)
Drizzle the pizzas with a little olive oil before placing under a preheated grill. Cook for about 4 minutes until the topping is golden and bubbling and the dough along the edges is nice and crisp.
Serve warm, cut into slices, and drizzle with extra olive oil with a couple of extra rosemary sprigs sprinkled on top.