To make the pizza dough, tip the flour into a bowl, put the yeast on one side and the salt on the other. Make a well in the centre and pour in 200ml warm water and the olive oil. Mix together with your hands to form a rough dough, then tip onto a lightly floured work surface and knead for 8-10 mins until smooth and springy. Put into an oiled bowl, cover with a tea towel and leave to rise until doubled in size, about 1 hr.
Heat the oven to 240C/220C fan/gas 9 and put a baking sheet inside to heat up. Knock the dough back into the bowl, then divide into two balls. Press the dough balls into flat rounds on a floured work surface, then roll into 5mm thick pizza bases, about 25cm wide. Transfer to two sheets of baking parchment.
Mix the passata, garlic and oregano in a small bowl with some seasoning. Spoon the sauce over the bases, leaving a 1cm border. Scatter with the finely grated Grana Padano and any of the toppings, if you like. Transfer the pizzas, cooking one at a time, onto the preheated tray with the baking parchment. Bake for 10 mins until the crusts are golden and crisp. Repeat with the remaining pizza.
Top the pizzas with the rocket and the Grana Padano shavings, then drizzle over the oil to serve.