Instructions: Butter a 10-inch tube pan and dust with flour or dry bread crumbs. Set a rack at the middle level of the oven and preheat to 350 degrees.

Place the chocolate in a heatproof bowl and place the bowl over a pan of hot, not simmering, water to melt. Remove the bowl from the pan when the chocolate has melted stir, then allow the chocolate to cool while preparing the rest of the ingredients.

Combine the flour, baking powder and salt in a bowl and stir well to mix. Set aside.

Use an electric mixer set at medium speed, to beat the butter and sugar until light, about 3 minutes. Beat in the eggs, 1 or 2 at a time, beating well between each addition (after all the eggs are added, the mixture may seem separated, this does not matter). Beat in the lemon zest, juice and 2 tablespoons of the rum. Gradually beat the flour mixture into the butter mixture. Remove 3 cups of the batter to a bowl. Stir remaining 3 tablespoons rum, milk and baking soda into the chocolate and immediately beat the chocolate mixture into the reserved batter.

Spread the chocolate batter evenly in the prepared pan, then top with the plain batter. Plunge a knife or spatula into the cake batter and cut up and down through the batter. Repeat every inch around the cake to marbleize the 2 batters.

Bake the cake about 1 hour, or until a knife inserted halfway between the edge of the pan and the tube emerges clean. Cool the cake in the pan on a rack for 15 minutes, then invert the cake to the rack to cool completely.

This recipe yields one 10-inch tube cake.

If you would like to email yourself the recipe for later use, or share the recipe with your friends or family, enter the email addresses below and this recipe will be emailed to you and others as well.