Preheat the oven as per your dough instructions - about 200C fan/220C/450F. Add the baking trays too, for a very crispy crust if you wish.

Peel and slice the potatoes into 1 cm thick pieces; stack and cut in half. Steam the potatoes for eight minutes. Rinse briefly, and drain in a sieve. Toss them with most of the chopped rosemary and 1 tbsp of the oil. Set aside.

Slice the leeks into thick coins. Heat the remaining oil and slowly sauté, adding salt and pepper, until soft and starting to colour.

Mix together the créme fraîche and lemon zest. Season with salt and pepper if liked.

Sprinkle polenta over two sheets of parchment and roll out the individual pizza bases as directed on packet or recipe. We like them pretty thin. If making a large sharing pizza, just use one large piece of parchment.

Spread the créme fraîche mixture over the pizzas, leaving the edges free. Add on the rosemary potatoes and the soft leeks. Sprinkle over the cheese. Grind over some pepper.

Slide the pizzas from the parchment onto the (hot) baking trays and bake until deeply golden-edged, and the potatoes and leeks have taken on good colour - about 15 minutes. You can also bake the pizzas on the parchment, so don't worry if you can't easily slide them onto the tray.

Remove from the oven and immediately drizzle the crust with extra olive oil if you wish. Sprinkle over optional chilli flakes and a goodly amount of nippy rocket leaves. Cut and serve between 2 and 4 people.