Start by breaking up your chocolate into a heatproof bowl, then add your butter and melt them together. This can be done in a Bain-marie (placing your bowl over a pan of simmering water, making sure the bowl is not touching the water) or in a microwave. I am a microwave melter all the way- just take it out and stir every 20 seconds or so to make sure it doesn’t burn.
Once your chocolate is melted, weigh in your caster sugar, mixed spice and cinnamon and whisk them together until combined.
Next whisk in your eggs and egg yolk, before sieving in the plain flour and mixing together.
Finally add your raisins to the mixture, make sure they’re drained if you’ve soaked them. You could swap these out with other dried fruit or nuts, like cranberries, sultanas or hazelnuts.
Pour the mixture into a line tin, ideally 8 x 8 inch, alternatively you can use a 6 x 10 inch, and bake in the oven for 35-40 mins. Once they’re baked, leave them to cool on the side for about 3 hours.