A few well-loved sauces depend on butter almost entirely. For these, nothing less than the freshest butter will do—unsalted is best, because it will not interfere with any other seasonings. The simplest of these, Brown Butter, and Beurre Meunière, are nothing more than seasoned butter cooked until it begins to brown and takes on marvelous nutty and toasty flavors. The slightly more complicated Beurre Blanc, derives its velvety smoothness from whisking in the butter so that it blends into and thickens the sauce without melting outright.
