To make the pastry, roll the sheet of puff pastry out onto a sheet of baking paper, lightly dusted with a little flour.
Fill with the mushroom mixture, leaving 2cm on either side.
Roll the pastry around the mushroom mixture and pinch the wellington closed to seal and trim any excess pastry.
Use a fork to gently score the pastry and brush all sides with the whisked egg.
Place in the fridge for an hour.
Next, it’s time to cook the wellington.
Preheat the oven to 190C and place the wellington, along with the baking paper underneath, onto a large baking tray.
Bake for 25 minutes before leaving to rest for 10 minutes.
Serve with mushroom gravy.
source: express.co.uk