1.Preheat oven to moderate, 180°C (160°C fan-forced).
2.Grease and line base and sides of a 24cm round springform pan with baking paper, extending paper 3cm above rim of pan.
3.Combine melted chocolate, butter, egg, flours, sugar, chocolate bits and macadamias in a large bowl. Press into base of prepared pan. Bake 25 minutes, or until lightly browned; cool in pan.
4.Combine ice-cream and berries. Spoon over base; level top. Cover: freeze 2 hours.
5.Heat reserved syrup in a small saucepan. Add extra sugar; cook and stir until sugar dissolves. Boil 2 minutes, or until reduced by half; cool. Slice cake. Serve drizzled with syrup.