Bring a litre of water to the boil and add the thyme and bay leaves. Add the chicken wings, reduce to a simmer and poach for 30 minutes.
Wash the leeks and slice into rounds. Heat a saucepan, add a little olive oil and a pinch of salt and cook for 15 minutes over a low heat.
Cut the foie gras into 25g pieces. Season with fleur de sel, black pepper and the white truffle oil.
Roll out the pasta sheets and brush half them with a little beaten egg yolk. Place a piece of foie gras to one side of each pasta sheet. Fold in half to close the ravioli, press the edges down and use a pastry cutter to trim one side, creating a half-moon shaped ravioli. Repeat until all of the foie gras and the pasta sheets have been used up.
Transfer a little of the chicken stock to a saucepan and bring to a gentle simmer. Cook the raviolis in this stock for 2-3 minutes then drain and set aside.
Reduce the remaining stock to 100ml and then add the cream. Mix and then filter to remove the chicken. Season with salt and pepper.
Serve the raviolis on a bed of leeks and finish with a drizzle of the chicken veloute.
«For a real gastronomic finish, finely slice some fresh truffles and sprinkle over the dish.»