1. Preheat oven to 180C. Put flour, bicarb soda, baking powder, salt and coffee in a bowl; whisk well. Stir in nuts and chocolate to coat in flour. Set aside.

2. In a mixer beat butter and sugar, scraping down the sides occasionally, for about six minutes until light and fluffy. Add eggs, one at a time, beating well after each, then mix in the vanilla.

3. Add reserved flour ingredients and mix in on low speed until combined.

4. Divide the dough in half. Roll each half into two log shapes about 24cm long. Carefully transfer these to a baking sheet lined with baking paper. Leave at least 6-7cm between them as they will flatten and spread.

5. Bake until becoming golden, about 35 minutes. Remove from oven and leave to cool. Reduce heat to 160C.

6. When logs are barely warm cut into 7mm-thick diagonal slices. Lay biscotti on baking sheets with a cut side down, return to oven. Bake until crisp and golden brown, about 15 minutes.

7. Remove from oven and cool on racks (biscuits will be fragile at first so be careful when you transfer them). When cool, store in airtight containers. If liked, spread one side of each biscotti with melted chocolate, then run a fork through it to create a pattern. Leave to set or place in freezer for about 10 minutes until chocolate has hardened. (In warm weather, it's better to coat them near to serving time.)

Tip: The mixture is quite soft when you shape it so use a knife or spatula to smooth it.

Tip: Hold the loaves firmly round the sides as you slice them to help prevent them breaking too much.

Tip: Use a small blunt knife or palette knife to coat one side of each biscotti in a fairly thick layer of melted chocolate.