Preheat the oven to 180C (350F) and line two baking trays with baking paper.

In the bowl of a food processor, process the walnuts, flour, cinnamon and a pinch of salt until very fine.

In the bowl of an electric mixer, beat the butter and half the icing sugar until pale and fluffy.

Pour in the vanilla and nut mixture and keep beating on low until it all comes together to form a dough.

Using a heaped teaspoon of dough at a time, roll it into balls and place on the baking trays leaving 3cm between each one.

Bake for 20-25 minutes or until they turn golden.

Transfer the biscuits to a wire rack to cool until they are able to be handled.

Place the rest of the icing sugar in a shallow bowl and toss the warm biscuits in it to coat.

When they have cooled completely, toss them in icing sugar again before serving.

Store in an airtight container for up to 4 days.