Using a shop-bought panettone takes some of the work out of this trifle. If the panettone is fresh, simply use it as is; if not, toasting it can bring it back to life. This trifle is free-form, so it can be assembled at the last minute; otherwise assemble it in advance and give it some time in the fridge - a couple of hours or even overnight - for the flavours to mingle. Serve it in individual glasses or bowls, or as one grand centrepiece. Start this recipe a day ahead to make the jelly.