Preheat the oven to 160C/325F/Gas Mark 3. Grease and line a baking tray.
Place the nuts onto a baking tray and place in a preheated oven for 10 – 12 minutes. Set aside to cool.
Beat the egg whites and sugar together in a bowl using an electric whisk to form a meringue. Sieve in the flour, and fold gently into the meringue mixture. Stir in the nuts.
Pour the mixture onto a baking tray and transfer to a preheated oven. Bake for 20 minutes then remove from the oven and cut into 2 cm slices lengthways.
Place the biscotti flat onto a baking tray and return to the oven, bake for a further 8 – 10 minutes until the biscotti are crisp and golden.
In the meantime, melt the chocolate in a bowl over a pan of simmering water. Once the chocolate has melted either dip the biscotti or drizzle the biscotti with the chocolate. Allow the chocolate to set before packaging.