Soak the dried mushrooms in 150ml warm water. Set aside for 20 mins, then drain and squeeze, reserving the soaking liquid. Heat the butter in a large frying pan. When sizzling, add the shallot and cook for a few mins until soft. Add the garlic and thyme leaves, cook for 1 min more, then turn up the heat and add the soaked mushrooms. After 1 min, add all the other mushrooms and fry over a very high heat for 5 mins until soft. Splash in the red wine and boil rapidly for 1 min. Pour in the stock and reserved mushroom liquid, and simmer for 15 mins until you have a thickened stew. Turn off the heat.
For the polenta, bring the milk to the boil with 500ml water, the bay and thyme. Turn off the heat and leave to infuse for 20 mins, then fish out the herbs and bring back to the boil. Add the polenta in a steady stream, whisking steadily. Cook for 1 min until thickened, then stir in the butter and Parmesan. Spoon a ‘crater’ of polenta onto a baking tray and fill with the ragout. Top with slices of Taleggio, place under a hot grill until melting and oozy, then let everyone help themselves.