Ingredients

2 tbsp Co-op olive oil 1.5kg Co-op British boneless beef roasting joint 4 tbsp English mustard 15g Co-op unsalted butter 2 x 200g packs chestnut mushrooms, finely chopped 2 cloves garlic, peeled and crushed Sprig fresh thyme (or 1 tbsp dried) 500g puff pastry 6 slices prosciutto 1 Co-op British free range egg, beaten;

Method

Preheat the oven to 200ºC/fan 180ºC/Gas 6 Lightly oil a baking tray Rub half the oil over the beef joint and sear in a heavy based frying pan, over a medium heat for 5 mins Remove from the pan and brush over the mustard Heat the remaining oil and butter in the pan and gently cook the mushrooms with the garlic and thyme for about 5 mins Roll the pastry out to a rectangle a few centimetres longer than the beef joint, and wide enough to fold over the joint, to encase it Arrange the slices of prosciutto across the pastry, then sit the beef in the middle of it. Spoon the cooked mushrooms over the beef Bring the proscuitto and pastry up and over the beef, then seal it and trim the ends Score the top, then brush with the beaten egg and place on the oiled baking tray Cook for 1 hour, until golden The beef should be slightly pink inside