Meanwhile, in a large, deep skillet, cook 4 tablespoons of the unsalted butter over moderate heat until lightly browned, 3 minutes. Add the chanterelles, season with salt and black pepper and cook over high heat, stirring occasionally, until all of the liquid has evaporated and the mushrooms are golden, 8 minutes. Add the shallot, thyme and crushed red pepper and cook over moderately high heat for 5 minutes, stirring. Add the vinegar and cook until evaporated, scraping up any browned bits from the bottom of the skillet. Add the stock and simmer until reduced by half, 10 minutes. Season with salt and black pepper.