Heated the oven to 250 C. Mix half the butter with salt, pepper and pressed garlic and stir the mixture. This mixture rubbed leg of lamb and put it in the tray. Around him arrange the sliced ​​two heads of garlic and bake about 20 minutes. Subtract the tray and sprinkle on the leg and around the thyme, pour the wine, pre-heated to boiling. Tightly close the pan with foil and bake for 2 hours and 45 minutes. Subtract leg of lamb and garlic from the pan. Put the pan on the stove, boil the sauce from baking, add the remaining butter and baked and crushed garlic and leave to boil until thickened, about 10 minutes. Forge to taste with salt and pepper and Serve the sauce with the leg.