Whisk 3 large eggs, 180 ml milk, 100 g plain flour and 1 tsp fine salt in a mixing bowl until smooth.

Chill the Yorkshire pudding batter in the refrigerator for 30 min, or freeze it for 15 min.

Pour 30 ml sunflower oil into the aluminium oven tray and heat it in the oven at 220°C for 15 min.

Pour the chilled batter into the hot tray so it reaches every edge.

Bake the Yorkshire pudding at 220°C for 10 min, then reduce the oven to 180°C.

Bake for a further 12 min until risen and cooked through.

Lay the Christmas leftovers in a long strip over aluminium foil and add the thick gravy.

Roll the foil tightly into a log and chill it in the refrigerator while making the duxelles.

Dice the onion and grate or finely chop the mushrooms.

Cook the onion in a frying pan over medium heat until softened.

Add mushrooms, garlic, mixed herbs, vinegar and a pinch of salt to the pan.

Cook the mushroom mixture until heavily reduced and all moisture has evaporated.

Transfer the duxelles to a bowl and let it cool completely.

Overlap 12 slices of prosciutto on a large sheet of cling film, making a rectangle wider than the leftover log.

Spread the cooled duxelles evenly over the prosciutto.

Place the chilled Yorkshire pudding and leftover log in the centre of the duxelles-covered prosciutto.

Use the cling film to roll the prosciutto tightly around the filling and pinch both ends closed.

Chill the wrapped log in the refrigerator for 15 min so it firms up.

Roll out the puff pastry on a lightly floured surface until it can fully enclose the log.

Unwrap the chilled log and place it in the centre of the puff pastry.

Brush the pastry edges with egg wash, then fold the pastry tightly around the log.

Seal the pastry seam underneath and trim any excess pastry.

Cut decorative pastry leaves from the trimmings and attach them with egg wash.

Brush the entire Wellington with egg wash and sprinkle it with sea salt flakes.

Bake at 180°C for 70 min for a large Wellington, until the pastry is deeply golden and the centre is hot.

Rest the Wellington for 15 min, then slice and serve hot.