Fruit curd is a dessert spread and topping usually made with citrus fruit, such as lemon, lime, orange or tangerine. Other flavor variations include passion fruit, mango, and berries such as raspberries, cranberries or blackberries. The basic ingredients are beaten egg yolks, sugar, fruit juice and zest which are gently cooked together until thick and then allowed to cool, forming a soft, smooth, intensely flavored spread. Some recipes also include egg whites and/or butter.