Heat a pan of water, tip in the potato slices and simmer for 5 mins until just cooked through.
Drain really well. Tip into a bowl with the olive oil and rosemary.
Mix together well so that the potatoes are completely coated in the oil.
Place the pizza bases on a baking sheet. Scatter the cheese over the pizza base, then arrange the potato mixture on top. Season with salt and pepper, then bake for 20 mins, until the pizza base is golden and the potatoes are starting to brown.
