put the wine and shallots into a pan and simmer, uncovered over a low heat for 20-30 minutes, or until the liquid is reduced by 2/3. Set aside to cool for 5-10 mins. Stir the butter, lemon juice and parsley together in a bowl, and gradually whisk in the reduced wine and shallot mixture. Add salt and pepper to taste. The butter should have a creamy consistency; it should not be chilled before serving.
