Technically, white chocolate is not a chocolate, but it tastes just as decadent! Macadamia nuts also work well and give a creamier flavour than pistachios.
Preheat the oven to 160 degC. Place 18 paper baking cups in muffin pans.
Combine all the cupcake ingredients, except the chocolate chips, in a large bowl and beat with an electric mixer until smooth and pale - about 2-3 minutes.
Stir in the chocolate chips. Spoon the batter into the cups.
Bake for 20 minutes. Remove the pans from the oven and cool for 5 minutes.
Then remove the cupcakes and cool on a rack.
To make the frosting, heat the chocolate and milk in a double boiler, stirring frequently, until the chocolate has melted.
Remove from the heat and beat in the icing sugar until smooth. Spread over the cupcakes and sprinkle with the nuts.