Beat butter sugar, salt and vanilla extract in a bowl.

Whisk in the eggs and baking powder

Fold flour, ground cinnamon, all spice (mixed spice) and cardamom (if using) into the mixture

Divide the dough in half

Place both dough halves onto a baking sheet lined with parchment (baking paper)

Shape each half into 10" x 5" (25 x 5 cm) logs, about ¾" (2 cm) tall.

Allow room for spreading otherwise the logs will stick together

Straighten the logs, and smooth their tops and sides (a wet spatula is helpful to get a neat smooth top).

Preheat the oven to 180°C/350°F (160°C fan). Position shelf in the middle of the oven.

Bake for 25 minutes

Remove the baked dough logs from the oven.

Reduce the oven temperature to 160°C/325°F (140°C fan).

Wait 5 minutes, then use a sharp knife or serrated knife to cut the log crosswise into ¾" (2cm) slices.

Place them back on the baking sheet with a cut side up.

Return the sliced biscotti to the oven, and bake them for 10 minutes, then flip the slices over (so that the underside crisps and dries as well)

Bake for another 5 to 8 minutes until they feel dry and are beginning to turn golden. They'll still feel soft in the center, but they'll continue to dry out as they cool.

Ensure that your utensils and cutlery are dry before melting the chocolate

Wet cutlery and utensils will cause the melted chocolate to seize and become unusable

Melt the chocolate in a dry medium bowl in the microwave (or use a double boiler).

The key to melting chocolate in the microwave is to do it in small bursts and stir frequently.

Melt in 15 second increments, stirring vigorously with a completely dry spoon after each increment, until completely melted and smooth.

Dip one end of the baked and cooled Biscotti in the melted chocolate. Leave to dry for a few minutes on a sheet of parchment paper before storing.

At room temperature: in an airtight container for up to 2 weeks.

To freeze: Biscotti can be frozen in an airtight container for up to 3 months.