Separate the egg white and the egg yolk.
Whisk together the egg yolk and the sugar. Add the flour to this mixture.
Melt the butter, white chocolate and the dark chocolate in a bain-marie or in the microwave. After cooling add it to the yolk/sugar mixture.
Stiffly beat the egg whites (with a pinch of salt) and fold them into the batter.
Cook it in the oven at 160°C during 15 min.
Crush the raspberries (keeping some for the decoration) with the lime juice and zest, and a teaspoon of sugar.
Allow the brownies to cool and serve with raspberries and a wedge of lime.