Check salmon for bones
Crumble cheese
Finely slice and wash leeks
Blanch for 2 mins, then refresh in cold water
Drain well and dry with kitchen paper
Mix together with butter, cheese and lemon juice
Spread the butter over one fillet
Cover with the leeks
Top with other fillet
Cut the pastry in half
Roll pastry to twice the width and length.
Prick base with fork
Place salmon sandwich on top
Roll remaining pastry slightly bigger to fit over the salmon
Egg edge of pastry
Put lid in place
Seal edges
Knock up edges and decorate
Brush with egg
Bake for 20 mins
Reduce oven temp Electric 190C/Fan 170C, Gas 5
Cook for another 20-25mins
Leave to rest for 5 mins before serving
Freeze at stage 18, allow to defrost and continue from stage 19