preheat oven to 180°F

slice the potatoes thinly on a mandolin if you have one

parboil the sliced potatoes for 5 minutes

simmer 300ml of the double cream with the milk and add 2 chopped cloves of garlic and the wholegrain mustard

season the cream to taste and remove from the heat. add half the cheese and some thyme

layer the potatoes in a deep baking tray with some of the cheese between each layer and finally use the remaining cheese to top the potatoes.

put the potatoes in the oven for 40 minutes being careful not to burn the top

finely chop one of the onions along with the celery.

chop 2 cloves of garlic and thinly slice the carrot slightly on an angle

peel the shallots and clean the mushrooms

In a heavy pan fry the lardons until browned and crispy, add the chopped vegetables, garlic, thyme and dijon mustard

fry for ten minutes then add the stock, wine and bouquet garni

reduce the sauce by half on a simmer for at least half an hour

chop the remaining onions and fry with some thyme in butter for half an hour being careful not to brown

after half an hour add 100 ml of the remaining cream to the onions then blitz to a fine puree with a hand blender or food processor

season the steak liberally with salt and black pepper

mix the cornflour in a little cold water until it dissolves then add to the wine and stock

fry the steak on a heavy griddle or pan for five minutes on each side in some butter and olive oil

leave to rest for at least five minutes

add the resting juices to the stock and wine

time to plate up

put a thick line of the onion puree on a white plate

using a round pastry cutter put a round of the potato at the end of the line of the onion puree

liberally drizzle the sauce around the puree with plenty of lardons, mushrooms and carrots

put the steak alongside the puree and enjoy