Pre heat oven to 350 degrees. Using a pastry brush, butter the cake pan well. Dust the pan with flour, shake out any remaining flour. Then dust, the pan well with unsweetened cocoa powder. Shake out any excess cocoa. Set aside.
In a large bowl, whisk together the 2 1/2 cups flour, salt, baking powder, baking soda, cinnamon, cloves, allspice, cardamom and nutmeg. Set aside.
In a stand mixer fitted with a paddle attachment, beat the 12 TBSP of butter and 1 1/2 cups light brown sugar until fluffy, and the sugar has dissolved. Add in the eggs, one at a time. Scrape down the bowl. Stir in the 1/2 cup molasses and vanilla.
Alternating, add in the flour mixture, water and rum. Add to the mixer a third each time: flour mixture, water, rum. Mix until just smooth- do not over-mix. Scrape down the bowl to make certain all the ingredients are well incorporated.
Pour the batter into the buttered and floured/cocoa dusted cake pan. Bake at 350 degrees for 45 minutes or until a cake tester inserted in the center of the cake comes out clean. It might help to place the bundt pan on a parchment lined rimmed baking sheet.
While the cake is baking heat, 1/3 cup rum ,1/4 tsp cinnamon, 1/4 tsp ginger and 3/4 cup sugar in a saucepan until sugar is dissolved.
Remove cake the from oven and let it rest on a wire rack for 10 minutes. Invert the pan onto a cake stand to release the cake. Using a pastry brush, glaze the entire cake with the warm rum mixture.
Let the cake cool another 30 minutes and dust with the sifted powdered sugar to create a snowy effect.
Save extra glaze for the serving table, add to your coffee, use as a sweetener for cocktails or to pour over ice cream.