dry coconut, halved, flesh removed and finely grated, to serve
chocolate (at least 60% cocoa solids), coarsely chopped
chocolate (50% cocoa solids), coarsely chopped
large eggs (67gm each), separated
plain flour, sifted
For chocolate ganache, melt chocolate and cream in a heatproof bowl placed over a saucepan of simmering water (5-7 minutes). Once chocolate melts, stir until glossy, then remove from heat and stir through rum. Cool at room temperature until ganache is thick but still pliable (2-3 hours, see note).
Meanwhile, for chocolate cakes, preheat oven to 190C. Melt chocolate and rum in a heatproof bowl placed over a saucepan of simmering water, then stir until smooth and glossy. Cool to room temperature, then stir through egg yolks, butter and flour. Meanwhile, whisk eggwhites in an electric mixer until soft peaks form, then with motor running gradually add sugar and whisk until smooth and glossy. Fold a third of eggwhite mixture through chocolate mixture, then fold in remaining eggwhite mixture. Spoon into 6 buttered and baking paper-lined 9cm-diameter cake tins and bake until risen (15-20 minutes). Cool completely on a wire rack, then turn cakes out and set aside. Coat cakes evenly with chocolate ganache and scatter with finely grated coconut to serve.
Note If ganache sets too quickly, briefly dip bowl in hot water to soften and stir until smooth.