Heat oven to 200C/180C fan/gas 6 for the friands. Melt the butter in a small pan, then remove from the heat and leave to cool a little. Grease 8 holes of a friand (or muffin) tin with a little bit of the butter.
Whizz 85g of the pistachios with the icing sugar until very finely chopped. Tip into a bowl with the ground almonds and flour. Roughly chop the remaining pistachios and set aside.
Froth the egg whites with a fork, then pour into the ground nuts and flour mixture with the melted butter and mix well. Pour into the friand tins, then scatter with the chopped pistachios and bake for 15-20 mins until the friands are risen, springy to the touch and a skewer inserted comes out clean.
Serve the friands warm, or at room temperature, with a scoop of chocolate ice cream, topped with a scattering of extra pistachios and a little chopped white chocolate, if you like. Delicious with a cup of coffee.