Preheat the oven to 160C. Zest the orange.
Whisk the egg whites to semi whipped. Add 150g of caster sugar and beat until you have a stiff and glossy meringue mixture.
Place the ground almonds and icing sugar and blitz to ensure that you have a very fine, lump free powder.
Fold the almond mixture in to the meringue. Cut and fold using a spatula until you have a smooth, shiny and ribbon-like mixture.
Pipe the macaroon mixture on to a lined baking tray, sprinkle with the orange zest then leave to rest at room temperature for 10 minutes. Place in the oven and bake for 10-15 mins.
Place the remaining 100g of caster sugar in a heavy based pan and allow to melt without stirring.
Once you have a golden caramel add the butter, cream and chocolate (broken in to pieces) and a pinch of salt.
Mix well and allow the chocolate to melt. Once fully incorporated, remove from the heat and allow to cool. Place in the fridge to cool further.
Fill half of the macaroon shells with the white chocolate caramel. Top with a second macaroon shells and serve.
«Place the macaroons in the fridge for a short while before serving - this will make them a little firmer.»