Cooking method:

1. Dry fry the bacon and mushrooms until cooked but not browned. Drain off any excess juices, add the mustard and pepper to the bacon mix. Set aside to cool.
2. Quickly pan fry the lamb fillets to seal and brown and set aside to cool.
3. Blanch and refresh the spinach leaves. Drain well and dry using kitchen paper.
4. Place a lamb fillet onto a spinach leaf. Top the fillet with one tbsp of bacon mixture and carefully roll up and encase the meat and filling in the spinach leaf, ending with the bacon filling facing upwards.
5. Repeat for each lamb fillet. Reserve excess bacon mixture to serve with accompanying sauce.
6. Roll out the puff pastry to 3mm thick. Cut into 2cm (¾in) wide strips and lightly brush with the egg and milk glaze.
7. Carefully wind the pastry strip, overlapping it slightly, around the spinach parcel. Take care to keep the bacon stuffed side facing upward for presentation purposes. Repeat for all the spinach parcels.
8. Place on a baking sheet, brush with glaze and bake in a pre-heated oven (200°C/400°F/Gas Mark 6) for 20-25 minutes, until golden and crisp. Reheat the reserved bacon mixture with reduced lamb stock. Add freshly chopped parsley. Serve the sauce with the lamb en croute.