The perfect sausages for this dish are those from specialist Italian or Continental delicatessens, luganega, which come in one long length. If you are using ordinary sausages, add a teaspoon of fennel seeds to the onions when frying.
There are three whole lemons used in the cake, icing and decoration so the flavour is incredibly intense and delicious. Equipment and preparation: you will need 2x 20cm/8in round sponge tins, greased and base lined with baking parchment.