Put raisins in a small bowl or airtight container and pour in the rum. Cover and let sit at room temperature for at least 8 hours, or overnight.

When you’re ready to bake, heat the oven to 350 degrees. Spread the chopped walnuts on a rimmed baking sheet and toast for 10 minutes, until fragrant; set aside to cool completely. Grease two 9-inch cake pans with oil, and line the bottoms with parchment paper.

In a medium bowl, whisk together the flour, cinnamon, ground ginger, baking powder, baking soda and salt.

Strain the raisins and place in a small bowl; save the rum in a separate container. In a separate medium bowl, mix together the carrots, toasted walnuts, pineapple, fresh ginger and ¾ cup of the rum-soaked raisins.

In a large bowl, whisk together the oil, granulated sugar and dark brown sugar until the mixture is no longer lumpy. Add the eggs one at a time, whisking thoroughly after each addition. Add 1 tablespoon of the reserved rum and whisk to incorporate.

Whisk in the dry ingredients until no dry streaks remain, and then fold in the carrot mixture.

Divide the batter evenly among both cake pans and bake for 30 to 35 minutes, until the tops of the cakes are springy to the touch and a toothpick inserted into the center comes out clean. Cool for 10 minutes in the pans, and then invert the layers onto a wire rack to cool completely.

While the cake layers cool, make the frosting: Beat the butter until spreadable. Add the powdered sugar and salt and begin beating together on low speed. Increase the speed and beat until the mixture is homogeneous. Add the lemon zest and 3 tablespoons of the reserved rum and beat until very smooth. Add the cream cheese a couple tablespoons at a time, making sure to beat thoroughly after each addition.

When ready to assemble, invert one cake layer onto a platter, flat side up. Spread about half of the frosting evenly over the layer and sprinkle the remaining rum-soaked raisins on top. Place the other cake layer on top and spread the remaining frosting on top. Adorn with chopped candied ginger, if desired.