Top and tail the gooseberries. Put them into a pan with the elderflower cordial. Bring up to the boil and then simmer gently until soft and pulpy. Leave to go cold, and then place in a serving dish.
Make the custard heat the milk up in a pan to the point of boiling. Beat the egg yolks, arrowroot and sugar together in a jug and pour the hot milk into the jug.. Mix well and then return to the pan. Heat gently until the custard thickens, but do not boil. Strain into a clean bowl and cool.
Whip the cream to the same consistency of the gooseberries.
Gently stir the cream into the gooseberries and then fold in the custard. Try to give it a marbled effect in the serving bowl. Place a few elderflowers on top to decorate.