1. Finely chop the shallot, measure the stock and cream, and trim the vegetables. Prepare a saucepan with a steamer basket and enough water to steam the vegetables without touching the bottom of the basket. Have a clean plate, foil and two warm serving plates ready. If serving with mash, prepare it separately and keep it warm.
2. Place the chicken between two sheets of baking paper on a sturdy board. Gently flatten the thickest parts with a rolling pin until each breast is approximately 2 cm thick throughout. Remove the paper, pat the chicken dry with kitchen paper and season both sides with salt and pepper. Wash your hands and clean any utensils and surfaces that have touched the raw chicken.
3. Heat the olive oil in a large frying pan over a medium heat. Add the chicken and cook for approximately 5–6 minutes on each side, reducing the heat if it browns too quickly. Check each breast with a clean meat thermometer inserted into its thickest part: the centre must reach 75°C and remain at or above that temperature for 30 seconds. Continue cooking if necessary; use the temperature check rather than the timing alone to judge when it is ready.
4. Transfer the cooked chicken to a warm, clean plate and cover loosely with foil. Keep the breasts whole while you make the sauce. Retain the golden-brown cooking juices in the frying pan, but remove any blackened pieces. Bring the water in the prepared steamer to a simmer, keeping the lid on until needed.
5. Reduce the frying pan heat to medium-low. Add the butter and shallot and cook for 3–4 minutes, stirring, until softened without browning. Pour in the stock and scrape the golden-brown cooking juices from the bottom of the pan with a wooden spoon. Increase the heat to medium and simmer until the liquid has reduced by approximately half, usually 2–4 minutes. When you add the stock, put the vegetables in the steamer and cover. Steam for approximately 4–6 minutes, until just tender. Once ready, remove the basket from the heat and keep the vegetables covered while you finish the sauce.
6. Reduce the frying pan heat to low. Stir in the double cream and simmer gently for 2–3 minutes, until the sauce lightly coats the back of a spoon. Return the chicken and its resting juices to the pan. Spoon the sauce over the breasts and warm gently for approximately 1–2 minutes, or longer if needed, until hot throughout. Avoid boiling vigorously. If the sauce becomes too thick, stir in water, 1 tablespoon at a time, until it is pourable.
7. Remove the frying pan from the heat and stir 2 tbsp of Summer Black Truffle Sauce into the cream sauce around the chicken. Taste and adjust the salt and pepper, adding a little more truffle sauce if desired. Divide the chicken and vegetables between the warm serving plates, spoon over the sauce and serve immediately. If you prefer sliced chicken, slice it just before plating.
