Beurre blanc (pronounced burr blong) is a classic butter sauce from the Loire Valley in France. It is made by whisking cubes of butter into a reduction of water, wine and shallots, then seasoning with lemon juice and salt and pepper. The finished sauce is a coating consistency. It is served warm, traditionally with poached fish and seafood or steamed vegetables.
Beurre noisette translates as ‘nut-brown butter’. It is not a thickened sauce. Butter is gently cooked until it turns a golden brown, then a little lemon juice is stirred in. It is served with pan fried fish.