Place the bacon in a bowl, pour over the beer and marinate in the refrigerator for 1 hour.
Preheat oven to 180degC (390degF). Wrap a bacon rasher around each of the steaks and secure with kitchen string. Reserve 185ml (3/4cup) of beer.
Heat a large non-stick frying pan over high heat. Brush the steaks with olive oil, sprinkle with salt and pepper and cook for 1-2 minutes on each side or until browned. Place on a baking tray and cook in the oven for 8 minutes for medium rare, or until cooked to your liking. Set aside and keep warm.
Heat the extra oil in a non-stick frying pan over high heat. Add the mushrooms and cook for 1-2 minutes or until browned. Add the stock and reserved beer and cook for a further 2 minutes or until slightly thickened.
To serve, place the steaks on serving plates, top with the Taleggio and spoon over the mushroom sauce.