Preheat oven to 150°C/300°F. Grease a deep 20cm (8-inch) round cake pan; line base with baking paper.
Place chocolate in a small heatproof bowl over a small saucepan of simmering water (don't let water touch base of bowl; Stir until chocolate is melted; remove from heat.
Sift flour, cocoa and cinnamon into a large bowl; stir in fruit and nuts. Combine honey, sugars and water in a small saucepan; stir over low heat until sugar dissolves. Simmer, uncovered, without stirring, 5 minutes. Pour hot syrup then melted chocolate into nut mixture; mix well.
Press mixture firmly into pan; press a 20cm (8-inch) round of baking paper on top.
Bake for 40 minutes; cool in pan. Remove panforte from pan, discard baking paper; wrap in foil. Stand overnight before cutting into thin wedges to serve.