Tip the stuffing mix into a bowl and pour over 420ml boiling water.
Add the spinach, give it a stir and leave for 15 minutes to cool.
Slit the sides of the sausages with a sharp knife to open them up. Add the sausage meat to the stuffing and discard the skins.
Season with salt and pepper.
Use your hands to mix the sausage with the stuffing so that it's evenly spread.
Heat the oven to 190C (fan)
Roll out the sheet of puff pastry.
Cut the pastry in half lengthways and then widthways so you have 4 pieces of pastry.
Place a couple of heaped dessert spoons on one half of the pastry (lengthways)
Move the sausagemeat into an even line 1cm from one of the edges, so it goes right up the ends and it's the same thickness all the way through.
Fold the other pastry over the top of the sausagemeat and press the edges firmly together.
Press the sausage roll gently so it's flat rather than rounded.
Use the prongs of a fork to make indents along the pastry join. Trim off any excess to neaten it and repeat with the other pastry and sausage meat.
Brush the pastry with beaten egg
Place on a lined baking and bake for 25-30 minutes or until golden brown and cooked through.
