It is made by whisking eggs and caster sugar and gently folding in flour. It can be topped with "kruszonka" (crumbles), meringue or a dusting of caster sugar. Welsh cakes are served hot or cold, sometimes dusted with caster sugar. The main ingredients are plain flour, butter, yeast, caster sugar, currants and sultanas. The biscuit is oblong in shape, and is lightly sprinkled with caster sugar. The most common food caster sugar is used in is meringue. Besides rose petal, it contains white caster sugar, water, and lemon juice. To assist in drying, powdered sugar or caster sugar is added during the tumble.