Combine the sugar and zest of one orange in a mixing bowl. Pour over the melted unsalted butter. Mix well to incorporate, and then stir in eggs one at a time. Next, squeeze over the egg mixture juice of one orange.
In a separate bowl, sift flour and combine with cocoa powder, baking powder, and a small pinch of salt.
Now, gently incorporate dry ingredients with the egg mixture. Meanwhile, melt the chocolate. Slowly stir in melted chocolate and then heavy cream. In the end, add in candied fruit. Scrape down the bowl's sides, ensuring all ingredients are well combined.
Preheat the oven to 350 °F.
Grease muffin pan with butter. Spoon the batter into the muffin cup, almost full. Send to the preheated oven and bake for about 20 minutes. As each oven is individual, and to ensure you do not overbake the cupcakes, check them for doneness with a toothpick after 15 minutes.
Once the chocolate orange cupcakes have cooled, decorate them with your favorite frosting or sprinkle some freshly shredded orange zest.