Lay out 8 slices of parma ham, Making sure it's overlapped, on a piece of clingfilm (don't cut the clingfilm off the roll).
Sprinkle black pepper over the parma ham
Use the back of a spoon to spread the mushroom paste thinly onto the parma ham. Leave 1/2 inch from the end
Lay the beef on top of the mushroom paste
Fold over the cut-end of the cling film and wrap the beef as tight as possible. Twist the ends of the clingfilm to get the shape
leave to set chill for 15 minutes
Place the 500g pastry on top of clingfilm
Put the beef fillet on top of the pastry
Roll the puff pastry over the beef until the 2 edges meet. Cut off excess pastry
Twist the ends together to ensure the beef is completely sealed
Wrap tightly in the clingfilm
Chill in the fridge for 5 minutes to firm up. (or until you're ready to cook it)