1.Preheat oven to 170°C/340°F. Line 18 holes of two 12-hole (⅓-cup/80ml) muffin pans with paper cases.
2.Break chocolate into large saucepan, add butter; stir over low heat until smooth. Whisk in sifted cocoa and sugars; cool 15 minutes.
3.Stir in extract and lightly beaten eggs, then sifted flour and rum. Stir raisins, half the cranberries and half the nuts into chocolate mixture.
4.Spoon mixture evenly into paper cases; sprinkle with remaining cranberries and nuts. Bake about 30 minutes. Cool cakes in pan.