3⁄4 cup dark rum
2⁄3 cup dried cherries
1 1⁄4 cups whole walnuts
1⁄3 cup finely chopped candied orange peel
1⁄4 cup finely chopped candied ginger
1 cup plus 1 1⁄2 Tbsp. sugar
10 1⁄2 tbsp. unsalted butter, softened, plus more for greasing
1⁄4 cup unsulphured molasses (not “blackstrap”)
1 large egg
1⁄3 cup plus 1 1⁄2 Tbsp. all-purpose flour
1 tsp. freshly ground black pepper
1 tsp. ground cinnamon
3⁄4 tsp. kosher salt
1⁄4 tsp. baking soda
1⁄4 tsp. freshly grated nutmeg
1⁄4 tsp. ground allspice
Four hours before you plan to bake the fruit cake, combine the rum and cherries in a small bowl and let stand for at least 4 hours, or overnight if you prefer. Drain the cherries, reserving the rum and transfer to a bowl along with the walnuts, candied orange, and candied ginger.
Heat the oven to 325°. Grease a 3 1⁄2-by-7-inch loaf pan and line with parchment paper. In a stand mixer fitted with the paddle, cream 1⁄2 cup plus 1 1⁄2 tablespoons of the sugar with the butter and molasses on medium speed until lightened in color and fluffy, about 2 minutes. Add the egg and continue mixing until combined, about 30 seconds. Turn the mixer off, scrape the paddle and bottom and sides of the bowl with a rubber spatula, then mix for 15 seconds until smooth.
In a medium bowl, whisk the flour with the pepper, cinnamon, salt, baking soda, nutmeg, and allspice. Using a large rubber spatula, fold the dry ingredients into the butter mixture until almost combined. Add the walnuts and dried fruit and until completely incorporated. Scrape the batter into the prepared loaf pan and bake until a toothpick inserted into the center of the cake comes out clean, about 55 to 65 minutes.
While the cake is baking, combine 1⁄2 cup of the reserved rum with the remaining 1⁄2 cup sugar and 1 tablespoon water in a small saucepan and heat over low, stirring to dissolve the sugar. When the cake is done, transfer the pan to a rack and brush with all of the rum syrup. Let the cake cool completely, then remove from the pan and serve, or wrap in plastic wrap and store at room temperature for up to 2 weeks.