Preheat oven to 350 °F (175 °C). Grease an 11×5-inch loaf pan.
In a saucepan over medium heat, combine sugar, vanilla, molasses, browning, honey, stout, raisins, cherries, and peel. Stir until bubbles form at the edges, then remove from heat.
In a large bowl, stir together flour, baking powder, salt, cinnamon, nutmeg, allspice, and ginger.
Add melted butter, beaten egg, and fruit mixture to the dry ingredients. Mix into a dough. Avoid overworking.
Transfer dough to the prepared pan. Bake for about 60 minutes or until a toothpick inserted comes out clean.
Once baked, brush the bun with simple syrup while still warm.
Let cool in the pan for 15 minutes, then turn out onto a wire rack to cool completely before slicing.