Heat oven to 220C/fan 200C/gas 7. 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.