One 12-cup Bundt pan, buttered and floured
Set a rack at the middle level of the oven and preheat to 350 degrees. Butter a 12-cup Bundt pan and flour the buttered surface, shaking out the excess.
Stir cake flour and baking powder together well to combine in a small bowl.
In a large mixing bowl, beat the butter until soft and light. Use a hand mixer set at medium speed or a heavy-duty mixer fitter with the paddle, if you have one. Gradually beat in the sugar and salt and continue beating about 5 minutes until very light. Beat in the eggs, one at a time, continuing to beat until the mixture is smooth and fluffy.
Sift half the cake flour mixture over the butter mixture, then stir it in. Stir in the milk thoroughly, scraping the side of the bowl, then sift over and stir in remaining cake flour mixture. Beat the batter for a few seconds to ensure that everything is thoroughly incorporated.
Divide the batter in half and stir the molasses and spices thoroughly into one half.
Spoon alternating tablespoons of the two batters into the prepared pan. Use the point of a table knife to run a zig-zag through the batters to marble them. Bake the cake for about 45 to 50 minutes, or until it is well risen and a skewer inserted in the center of the cake emerges clean. Cool in pan on rack for 5 minutes, then invert to a rack to cool.
Butter Bundt pans with very, soft, not melted butter. Dust the buttered surface with flour or fine dry bread crumbs.
Always use an insulated or doubled cookie sheet in the bottom level of the oven to prevent cookies from burning.