Preheat the oven to 220C/425F/Gas 7.
Brush an ovenproof dish with melted butter and then coat with the grated chocolate.
Place the strawberries into a food processor and blend until smooth. Transfer to a bowl and stir in the sugar and egg yolks.
In a separate bowl, whisk the egg whites until stiff then fold into the strawberry mixture.
Pour the mixture into the dish and place in the oven and bake for 8-10 minutes, or until well risen and golden.
Remove from the oven and dust with icing sugar to serve.