Place the shallots in a large heat proof bowl. Pour boiling water over them and leave them to stand for 5- 10 minutes. This will loosen the skin and make it easier to peel them.In a medium saucepan melt the butter and then fry the shallots until golden- but do not allow them to burn. Now add enough water to just cover the shallots and cook hem tover a medium to low heat for about 40 minutes. Keep an eye on them and keep adding water if they require more liquid. When the shallots are quite syrupy and tender add the sugar and the raisins. Keep cooking on a low heat until completely soft and almost like jam.
You can prepare these a few days before and then just reheat them before serving.