Bring dried mushrooms and stock to a boil, then strain, keeping the mushrooms warm. Melt butter in a saucepan and cook onion until golden. Add arborio rice, cook until lightly toasted, then add wine and cook until evaporated. Now, pour a glass of wine for yourself to enjoy while you add ½ cup of broth to the rice and stir until absorbed. Continue doing this until rice is tender and creamy, about 16 minutes. Add some minced mushrooms to the risotto, and in the meantime, toss the rest of the mushrooms with oil, thyme, garlic, and salt, and roast in the oven until mushrooms are browned and garlic is tender. Add peeled and mashed garlic, créme fraîche, parmesan, salt and pepper, and half the roasted mushrooms to the risotto. Garnish with the remaining mushrooms.