For the pastry, place the flour in a mound on a clean work surface and make a well in the centre.
Place the butter and salt in the well and work them together with the fingertips of one hand, gradually drawing the flour into the centre with the other hand.
When the cubes of butter have become small pieces and the dough is grainy, gradually add the iced water and mix until it is all incorporated, but don’t overwork the dough – you should have a marbled effect with the butter without mixing it in properly.
Roll the mixture into a ball, wrap in cling film and refrigerate for 20 minutes.
Flour the work surface and roll out the pastry into a 40x20cm/16x8in rectangle.
Fold the top third down to the centre, then the bottom third up and over that. Give it a quarter-turn.
Roll the block of pastry into a 40x20cm/16x8in rectangle as before, and fold it into three again. These are the first two turns. Wrap the block in cling film and refrigerate it for 30 minutes.
Give the chilled pastry another two turns, rolling and folding as before. This makes a total of four turns. Wrap the pastry in cling film and refrigerate for at least 30 minutes before using.
For the pancakes, place the eggs and flour into a bowl and whisk together.
Gradually add the milk, whisking constantly, to create a smooth batter that will coat the back of a spoon.
Heat a frying pan over a high heat and add the butter. When the butter is foaming, add a ladleful of the pancake batter and swirl the pan to evenly coat the base. Fry for 1-2 minutes, or until the underside is golden-brown. Carefully flip the pancake over and cook for a further minute, or until the pancake is cooked through and golden-brown all over. Slide the pancake out onto a plate lined with greaseproof paper, then cover with another layer of paper. Repeat with the remaining pancake batter to make another pancake.
For the duxelle, heat the butter in the frying pan until foaming, then add the mushrooms and fry for 3-4 minutes, or until the mushrooms are golden-brown. Season well with salt and freshly ground black pepper, then set aside to cool.
For the beef Wellington, preheat the oven to 200C/400F/Gas 6.
Season the beef fillet with black pepper then place into a frying pan over a high heat. Turn the fillet to ensure even cooking. Remove when browned on each side and leave to rest in a warm place.
Roll out the puff pastry until 5mm/¼in thick. Take two pancakes and place into the centre of the pastry, and cover with a layer of chicken liver pâté, then a layer of the cooked mushrooms, then a layer of spinach on top.
Beat the beaten egg and egg yolk together in a bowl, then brush the egg over the clear area of the pancakes and pastry and fold the pastry around to enclose the beef. Press the open ends together to seal the pastry covering and make it a close fit to the beef. Trim off any excess pastry.
Place the beef Wellington seam-side down onto a baking tray lined with baking parchment and brush with the beaten egg. Place in the fridge to cool for 30 minutes.
Remove from the fridge and brush with egg once more.
Place into the oven and bake for 25 minutes (if you do not like your beef rare cook for 30-35 minutes for medium), or until the pastry is golden-brown, then remove and leave to rest on a serving plate for 15 minutes.
For the purple sprouting broccoli and jus, place a large pan of boiling water on the hob. Once boiling, place the broccoli in the pan and cook for 3-4 minutes.
Drain the broccoli and heat a large frying pan and add the oil. Once hot, add the broccoli and cook for 2-3 minutes.
Place the stock in a pan and boil to reduce in volume by half. Add the red wine and reduce again to half the volume.
To serve, cut the Wellington into portions and place on a plate serve with the broccoli and jus.