To make the sauce, heat a pan and add the oil and butter, then swirl until the butter has melted and is foaming. Tip in the mushrooms and shallot and sauté for 2–3 minutes, until tender. Season with black pepper & stir well. Pour over the whiskey, then use a match or tilt up the pan to catch the flame. It will flare up for 5–10 seconds and then subside when the alcohol burns off. Add the white wine & Worchester sauce, stirring to combine, then simmer until reduced by half.
Stir in the beef stock bring to the boil & then simmer. Next add cooking cream. Simmer for 2 minutes, stirring occasionally, until thickened and reduced to a thick consistency. To finish, stir in the parsley, lemon juice & sugar. Season to taste & keep warm whilst cooking steaks.
Heat the rapeseed oil in a heavy-based ovenproof frying pan over a high heat. Season the steaks with the black pepper and cook for 2 minutes on each side to seal in the juices, then transfer to the oven and cook the steak for another 5–10 minutes, turning once, depending on how rare you like your meat (5 minutes for rare, 7 for medium and 10 for well done).
To serve, transfer the cooked steak to warmed serving plates, season with salt and set aside in a warm place to rest while you assemble the dish. Pour any juices that run off the meat into your whiskey sauce for added flavour. Drizzle the whiskey sauce around the steaks. Serve with mashed potato & your choice of vegetables or home-made fries a fresh green salad.
COOK AHEAD: Use the pepper sauce immediately or allow to cool down completely and store in a bowl covered with clingfilm in the fridge for up to 2 days. Reheat gently in a pan when needed.