Step 1

Preheat oven to 200°C. Line a large baking tray with baking paper.

Step 2

Combine beef, onion, garlic, tomato paste, herbs, crumbs, Worcestershire, mushrooms, half the egg and 2 tablespoons mustard in a bowl. Season and set aside.

Step 3

Cut 2 pastry sheets in half. Top each half with 2 slices prosciutto, then sprinkle with extra breadcrumbs. Divide beef into 4 portions, roll into thick logs and place onto pastry sheets. Fold over to seal, then place, seam-side down, on the baking tray.

Step 4

Slice remaining pastry sheet into 1cm-wide strips and use to decorate Wellingtons in a lattice pattern. Brush with remaining egg and bake for 20-30 minutes until pastry is golden. Rest for 5 minutes.

Step 5

Combine remaining mustard with creme fraiche and season. Serve the Wellingtons with mustard creme fraiche and spinach.