Preheat the oven to 180ºC/350ºF/gas 4. Lay out 6 sheets of pastry on a clean tea towel, overlapping each by an inch or so, so they cover the tea towel. They should cover it completely, with just a little overhang at one of the shorter ends. Work quickly so your pastry doesn’t dry out and brush some melted butter all over it. Sprinkle over the cinnamon and 50g of the sugar then crumble over your ginger nuts to add a nice bit of crunch. Carefully layer the rest of the pastry sheets on top and brush again with butter.