1. Melt the butter in a small saucepan and cook until brown.
2. Sift the flour,baking powder and sugar into a bowl.
3. In a separate bowl,whisk the egg with the milk. Pour this into the flour mixture and whisk until combined,then add the vanilla and whisk again. Gradually pour in the browned butter and whisk well,then whisk in the orange zest. Allow the mixture to rest for 1-2 hours in the fridge.
4. Preheat the oven to 170C. Butter madeleine moulds,coating well. Spoon or pipe the mixture into the moulds and bake for 6-10 minutes,or until golden.
5. Tap the madeleines out of the moulds onto a rack to cool briefly,then dust with icing sugar before serving.
TIP: The madeleine mixture keeps for 3-4 days in the fridge.
Serving suggestion: Serve with Frank'schilled chocolate pots