Preheat the oven to 190°C, gas mark 5. Make the mushroom duxelle mix. Put the mixed mushrooms in a food processor and pulse to a rough dice. Heat the butter in a frying pan and fry the onion and garlic until softened but not coloured. Add the chopped mushrooms and cook, again without colouring, for 5 minutes. Season, and then add the thyme and sage. Leave to cool.
Next, make the pancakes. Mix the ingredients in a jug. Heat the butter in a small frying pan and pour two-thirds of it into a small bowl to keep aside for brushing the pan in between pancakes.
Pour a small amount of batter into the frying pan and swirl it around to cover the base of the pan. Cook for 1-2 minutes and then flip and cook for another minute. Remove the pancake from the pan to a plate and continue to cook 5 more pancakes. Layer the pancake with greaseproof paper in between and leave to cool.
Season and seal the beef fillet and set aside. Mix the cooled mushroom duxelle with the pâté in a mixing bowl. Brush the large sheet of pastry with egg was. Layer the pancakes over the top of the pastry so that it’s covered and then use a palette knife to spread the mushroom mixture on top. Place the beef fillet on top of the mushroom mixture and roll up the pastry, making sure the beef is completely surrounded by the mushroom mix and the pancakes are well sealed. Leave to chill.
Place the Wellington on a baking tray and brush the top with beaten egg. Bake in the oven for 30 minutes, or to your liking.
Recipe courtesy of Lisa Faulkner