Heat oven to 200c
On a floured surface roll out the pastry till really thin
Using a potato masher , mash down your leftover filling
Spread the filling over the pastry
Roll it up tightly
Brush the edge with egg to seal
Cut into slices about 1-1.5 inches thick
Lay on a lined baking sheet and brush with the egg
Bake on the top shelf until golden ( 15-20 minutes )
Serve hot as a dinner with potatoes and veg or cold as nibbles