Peel the Jerusalem artichokes, placing each one in cold water to stop them discolouring.
Peel and finely dice the shallot and the garlic.
Pick the thyme leaves.
Slice the artichokes very thinly using a mandolin or a very sharp knife.
Sweat the shallots in melted butter with a pinch of salt. Once soft, add the artichokes, garlic and thyme. Season with salt and cook for 3 minutes before covering with chicken stock.
Cook for 20 minutes until the artichokes are completely soft, adding more stock if necessary.
Add the double cream, bring to the boil and then blitz in a food processor until smooth. Pass through a sieve and keep warm until ready to serve.
Heat a frying pan to very hot. Season the foie gras with salt and then add to the pan. Cook for 30 seconds and then turn over.
Remove the pan from heat and allow the foie gras to finish cooking.