• Preheat the oven to 180°C
• Put 150g chocolate into a heatproof bowl. Set over a pan of steaming hot but not boiling water (don’t let the base of the bowl touch the hot water) and melt very gently, stirring frequently.
• Remove the bowl from the heat and stir until smooth. Add the butter and stir until it has melted.
• Put the eggs into a mixing bowl and whisk with an electric mixer until frothy. Add the sugar and orange zest and whisk on high speed for about 4 minutes until the mixture is very thick and mousse-like, and the whisk leaves a ribbon-like trail when lifted from the bowl.
• Give the chocolate and butter mixture a stir, then add to the egg mixture and stir briefly – it should be just combined.
• Sift the flour into the bowl and gently fold in using a large metal spoon.
• Divide the mixture between the prepared tins and spread evenly. Bake for 15-20 minutes or until the sponges are light golden brown and springy to the touch.
• Run a round-bladed knife around the inside of the tins to loosen the sponges, then turn out onto a wire rack and leave to cool.

To Assemble

• Wipe the strawberries with kitchen paper and hull. Save one-third for decoration; thinly slice the rest into a bowl.
• Add the orange zest and juice and the sugar and mix gently. Leave for 10 to 30 minutes to allow the flavours to develop. 
• Whip the cream until thick, then gently stir in the orange curd.
• Set one sponge, top side down on a serving plate. Spoon the sliced strawberries and juice onto the sponge to cover evenly. 
• Spread half the whipped cream on top of the strawberries. Set the second sponge, top up, on the cream. 

To decorate

• Carefully spread the rest of the cream over the top of the cake and pile the reserved strawberries into halves and pile onto the top of the cake.   
• If you are serving straight away, sprinkle the to of the cake with grated white chocolate.