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