- Toast the hazelnuts in a dry pan until golden, then leave to cool slightly and blitz to a fine consistency in a food processor. Remove the cardamom seeds from their pods and grind using a pestle and mortar.
- Heat oven to 160C/140C fan/gas 3. Grease and line the base of a 23cm spring-form cake tin. Use a microwave to melt the chocolate with the butter in 30-sec bursts until glossy and smooth. Leave to cool slightly.