Butter that has been clarified of its milk solids not only raises the temperature at which it can be cooked without burning, it also helps the butter last longer (up to 1 month) and so is useful for sealing. It is worth clarifying reasonable amounts of butter at a time, remelting as required. First melt the butter slowly in a heavy-based saucepan. Pour the melted butter carefully through a sieve lined with muslin into a bowl, leaving as much of the milk sediment behind as possible. Allow to settle then pour gently again into another bowl or jug or pour on top of pâtés as required.