Cut cake into thick slices, sandwich together with jam and cut into rough chunks. Fit into base of a large, crystal bowl jigsaw-fashion, jamming them all together to cover the bottom. Soak with sherry liberally. Sprinkle over the raspberries and their syrup.
Make the custard: In a bowl, beat together the egg yolks, cornflour, vanilla and sugar. Bring the cream to the boil (I use a microwave) and pour over the yolks whisking vigourously. Return the bowl to the microwave and heat, whisking frequently until the custard has thickened. Do not over-heat or it may curdle. It should just start to bubble in the middle.
Pour custard over the fruit and allow to go absolutely cold. Chill, covered, in the refrigerator.
Just before serving, whip the cream until floppy (do not over-beat) and spread over the top. Decorate with cherries and almonds.
This will keep refrigerated overnight but a lot of liquid collects in the bottom and it doesn't look very attractive - still tastes great though!