Preheat the oven to 200C/ 400F/ GM 6 and line 2 baking sheets with baking parchment
Divide the dough into 4 each pieces and roll each out to a thickness of 2mm. Cut a 22cm circle from each (find a suitably sized plate as a guide to cut around)
Spoon a quarter of the filling into the centre of one pastry circle
Brush a little beaten egg around the edge of half of the circle then carefully fold the pastry over to form a semi-circle, join the dry and egg brushed edges together. Tuck any stray bits of filling back in as you go and then press down around the pastry edge to seal. Repeat with the remaining circles
Crimp the edges of each pasty to seal firmly and avoid any leakage during cooking: use your index finger and thumb to push down and twist the edge of the pastry over to form a crimp. Repeat this process along the entire length of the pasty then tuck the ends underneath (see my video for visual guidance)
Place the pasties on the baking sheets and make a small slit on the top of each one using a sharp knife, brush all over with beaten egg
Bake for 15 minutes then turn down the heat to 150C/ 300F/ GM 2 and bake for a further 45 minutes
Remove from the oven and transfer the pasties to a wire rack to cool for 20 minutes before eating