200 g (7 oz) unpeeled new potatoes, very thinly sliced on a mandolin
1/2 onion, very thinly sliced on a mandolin
2 teaspoons dried thyme
100 g (3 1/2 oz) Emmental or Cheddar cheese, grated
12 black olives (optional)
cracked black pepper
Preheat the oven to 200°C (400°F), Gas Mark 6, and lightly grease a baking sheet. In a large bowl, mix together the flour, yeast, sugar and salt. Make a well in the centre and pour in the warm water and 2 tablespoons of the oil. Combine to make a soft dough, then roll out to a rectangle about 35 x 25 cm (14 x 10 inches). Transfer to the baking sheet and cook in the preheated oven for 5 minutes or until just beginning to colour.
Spoon 4 tablespoons of the crème fraîche over the pizza base. Top with the slices of potato and onion, then sprinkle over the thyme and scatter with the cheese. Drizzle the remaining oil over the pizza and return to the oven. Increase the temperature to 220°C (425°F), Gas Mark 7, and bake for about 15 minutes, until golden.
Cut the pizza into slices, scatter with the olives, if desired, and top with the remaining crème fraîche. Season with cracked black pepper and serve hot.