Add the butter to a microwave safe bowl and heat in the microwave on a high heat setting for 1 min. Stir the butter until fully melted and set aside.
Using a stand or hand mixer with the whisk attachment, whisk the eggs and sugar together for 5 mins on a medium setting.
In a separate bowl, mix together the flour and baking powder.
Gently fold the flour into the egg and sugar mixture.
Add the melted butter and orange zest (or extract) and fold until combined.
Cover the madeleine mixture with cling film and pop it in the fridge to chill for 30 mins.
Preheat the oven to 200°C/180°C fan and lightly grease your madeleine pan with melted butter.
Equally spoon the mixture into each madeleine mould.
Bake in the oven for approx. 10 mins, then turn out the madeleines onto a wire rack to cool.
Break up the chocolate into a microwave safe bowl and heat in 30 second intervals in the microwave on a high heat setting, stirring in between until smooth.
Dunk the top of each madeleine into the chocolate and sprinkle with chopped walnuts.
Allow the chocolate to set and enjoy!
