Make the pasta frolla. Put the flour and butter pieces in a food processor with a little salt, and pulse until it has the consistency of breadcrumbs. Immediately add the water and pulse for a second to combine. Gather the dough together into a ball, wrap in cling film and place in the refrigerator for 1 hour.
Heat the oven to 200°C/400°F/Gas 6, and have ready a large flat baking tray.</