Make the jelly first so that it has time to set. Pour 30ml boiling water into a jug and sprinkle the gelatine over it, then whisk carefully until it dissolves. Pour in the strawberry juice while whisking, to make sure it’s properly mixed.
Place the sliced strawberries into a serving dish. Pour the jelly mixture over the sliced strawberries, filling the dish to about 10cm deep. Refrigerate for about 4 hours or until fully set.
Pour the custard into a pan with the chocolate pieces. Gently heat, stirring, until the chocolate has melted into the custard. Cover with clingfilm and cool.
Place one layer of the basic sponge on top of the set strawberry jelly. Gently pour over the chocolate custard. Top the custard with the second layer of sponge.
Gently spoon the softly whipped cream on top of the sponge and arrange the cherries on top.