Firstly, defrost the pastry, following the packet guide. Once defrosted, lay out some flour on the side and roll out the pastry with a rolling pin til roughly a millimeter thick.
Heat up the condenced soup in a saucepan like any other soup.
Get an ovenproof dish and line it with the pastry, making sure it hangs over the side by at least 3cm. Then add the heated condenced soup and anything else you may with to add for example sweetcorn or mushrooms.
Put another layer of pastry on the top, sealing it with the base (the 3cm flap) using the wisked egg. Cut off excess.
Then with the rest of the egg, glaze the top of the pie by brushing the egg on top and stab a few holes in the top to avoid it exploding!!
Place it in the oven until pastry is golden brown and crusty. Done!