Finely chop the onion, mushroom and garlic.
fry gently with a splash of olive oil until soft.
Add the spinach and fry until softened slightly.
Add salt and pepper to taste.
Cut the pastry in half, roll out each piece so that it is an inch wider than the salmon fillet.
Place one piece of the pastry on a well oiled baking sheet and place the salmon in the middle.
Brush the edges of the pastry with beaten egg.
Spoon the spinach mixture over the top of the salmon and spread evenly.
Top with the remaining pastry making sure the edges are well sealed.
Lightly score the pastry with a sharp knife and then brush with beaten egg.
Bake in a preheated oven at 180°C/160°C/Gas 4 for 40-45 minutes.
4 servings