Preheat the oven to 180ºC/Fan 180ºC/Gas 4. Mix the cornflour and orange juice together in the base of a medium saucepan. Add the strawberries, blueberries and sugar to the pan then cook over a medium to low heat for 4-5 minutes, stirring until the berries begin to soften slightly. Spoon into 4 x 250ml individual ovenproof dishes.
To make the crumble add the flour, sugar and butter to a mixing bowl and rub in the butter with fingertips or an electric mixer until fine crumbs. Stir in the marzipan and orange rind.
Spoon the crumble over the fruit and bake for 20-25 minutes until the crumble is golden brown and the juices are bubbling around the edges. Serve with scoops of vanilla ice cream.