Combine the fruit with the whisky in a non-reactive bowl; cover and let rest overnight.
Preheat the oven to 300°F/148°C. Prepare a springform pan by greasing and flouring it. Add parchment paper and grease and flour that as well. Use muffin pan liners for the muffin pan.
For the Nuts
Mix the nuts and chocolate. Set them aside.
For the Batter
Place the butter and sugar in a large bowl and beat together until well combined.
Beat in the salt, spices, and baking powder.
Beat in the eggs one at a time, scraping the bowl after each addition.
In a separate bowl, whisk together the flour and cocoa.
In a separate bowl, combine the molasses and honey to make a syrup. Next, put the espresso powder in a heatproof bowl or measuring cup and stir in the boiling water.
Add the flour mixture and the syrup to the mix in the bowl, beating gently to combine.
Stir in the espresso, then the fruit (including any additional liquid collected in the bowl), and the nuts. Scrape the bottom and sides of the bowl, and stir until everything is well combined.
Spoon the batter into the pans, filling them about 3/4 full.
Decorate the top of the cake with the orange slices, walnuts, and a cherry half. Put a single cherry on top of each muffin top.
Bake the cakes on the middle shelf of the oven, as follows: about 60 minutes for the individual cakes; 65 to 70 minutes for the small loaves; 75 minutes for the medium loaves, and 2 hours + 10 to 15 minutes for the 9" x 5" loaves. The cakes are done when a cake tester inserted into the center comes out clean.
Remove the cakes from the oven. Fruitcake can remain in its pan for storage if desired. Or carefully remove the cake from the pan after about 5 minutes, loosening its edges first.
Combine the rum and the simple syrup.
Brush the warm cake with the rum mixture. When the cakes are completely cool, wrap them tightly in plastic wrap, and store them at room temperature for 6 to 8 weeks. Then, paint them occasionally with more rum.
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