Sharp, yet sweet and comforting, this is a really satisfying thing to make. Old-fashioned in a way, it has a deep, nostalgic flavour, triggering memories – flavours that achieve this are particularly special to me. You can vary the taste by adding the juice of other citrus fruit, like blood oranges, as I have here. But don’t be tempted to omit the lemon altogether as its acidity is needed to prevent the curd from becoming overly sweet.