Ingredients

Step by step

1. To make the duxelles, heat the oil in a frying pan and fry the mushroom with seasoning for 5 minutes until golden brown. Add the shallot and garlic and cook, stirring, for 3-4 minutes. Remove from the pan and leave to cool, then very finely chop and set aside.
2. For the mousse, blend the chicken, egg whites and salt in a food processor or blender until smooth. Transfer to a bowl. Fold in the mushroom mixture and double cream, then set aside in the fridge.
3. For the crêpes, tip the flour into a bowl with a large pinch of salt, then make a well and crack in the eggs. Gradually whisk the eggs into the flour, then gradually whisk in the milk to form a smooth batter. Lightly grease a large non-stick frying pan (about 22cm base diameter) with a little of the oil. Place over a medium heat and, once hot, pour in just enough batter to make a thin crêpe, quickly tilting the pan to coat the surface. Cook for 1-2 minutes on each side until golden, then transfer to a plate. Repeat with the remaining batter, adding extra oil as necessary, until you have about 6 crêpes in total. Stack on a plate, separated by layers of baking paper. Leave to cool.
4. Lay out four large pieces of clingfilm and place a crêpe in the centre of each. Divide the chicken mousse between each crêpe, spreading to a circle the thickness of a pound coin and leaving a two-finger border around the edges. Season the beef fillets well and brush with the mustard. Place in the centre of the mousse and fold over the edges of the crêpe to seal, cutting and using the 2 spare crêpes to fill gaps, if necessary. Use the clingfilm to wrap tightly into a parcel. Chill in the fridge for at least 30 minutes.
5. On a lightly floured surface, roll out each sheet of puff pastry to make a slightly thinner 25cm x 35cm rectangle. Cut each sheet in half so you have four smaller rectangles. Unroll the beef fillets from the clingfilm and place a fillet at the end of each pastry rectangle, leaving a sufficient border to seal. Brush the egg wash around the beef. Fold over the pastry and seal to make a parcel, using a fork to crimp the edges. Trim off any excess pastry so you’re left with a neat pillow shape. Transfer the Wellingtons to a baking paper-lined tray. Brush with the egg wash again, then sprinkle over some poppy or sesame seeds, if you like. Chill in the fridge for at least 1 hour before cooking, or freeze at this stage, adding extra time to the baking when thawed.
6. Preheat the oven to 220°C, fan 200°C, gas 7 and put in a large baking tray to heat up. Transfer the Wellingtons to the preheated tray and roast for 20-25 minutes for medium-rare. If you have a digital probe, use it to check the internal temperature of the beef; the centre needs to reach 50°C for rare, 60°C for medium-rare, 65°C for medium, 70°C for medium-well-done, or 75°C for well-done. Once cooked, allow to rest for 20-30 minutes. Cut each Wellington in half and serve with gravy and seasonal vegetables of your choice.