Place the flour in a mixing bowl and add the salt, yeast and butter. Rub the butter into the flour until the mixture resembles fine breadcrumbs.
Heat the milk and water together until luke warm, then add to the flour mixture and mix to a soft dough. Cover and leave in a warm place for 30 minutes.
Preheat the oven to 230℃ (210℃ fan)/450°F/gas mark 8. Lightly grease two baking sheets with olive oil.
Divide the dough into two pieces. Lightly oil the work surface to prevent the dough from sticking and roll out one piece into thin rectangle about 35 x 25 cm (14x10 in).
Carefully lift onto a baking sheet , the dough is elastic so may shrink back in size, if so gently pull to stretch it back again. Brush all over with olive oil and then sprinkle with half of the caster sugar and half of the nuts if using.
Repeat with the second piece of dough then bake in the oven for 8–10 minutes until crisp and golden.
Nutrition information is approximate and is meant as a guideline only.