- 4¼ cups sifted cake flour
- 2 tsp. baking powder
- ⅛ tsp. salt
- 6 oz. semisweet chocolate, finely chopped
- 2 cups unsalted butter, softened
- 3 cups granulated sugar
- 1 Tbsp. vanilla
- 10 large eggs
- 2 Tbsp. milk
- Zest of 2 lemons
- Adjust rack one-third up from bottom of oven; preheat oven to 325 degrees. Grease tube pan. Line the bottom with a circle of wax paper cut to fit; grease the paper then lightly flour the entire inside of the pan (including the tube), knocking out any excess. Set aside.
- Sift together cake flour, baking powder, and salt; set aside. Melt the chopped chocolate in the microwave stirring at 15 second intervals; set aside.
- In a large mixing bowl, beat softened butter at medium speed until smooth. Add sugar and vanilla. Beat at a low speed until incorporated, scraping beaters and bowl with rubber spatula often. Increase speed to medium; beat for 3 full minutes. At a low speed add eggs, two at a time. When all the eggs have been added, increase to medium and beat for 1 minute. (Mixture may look curdled; that’s okay.)
- At lowest speed, add about half of the sifted dry ingredients, mixing only until blended. Add milk. Mix in remaining dry ingredients. Using a rubber spatula, fold in the lemon zest. You now have a large amount of thick, heavy batter.
- Measure out a generous 4 cups of batter and set aside. To remaining batter add the melted chocolate all at once; whisk in with a large, sturdy whisk.
- Alternate spoonfuls of dark and light batters into prepared pan. To level batter, grasp pan on opposite sides with both hands; twist briskly in short, back-and-forth motions. To marble, run a knife in a circular motion all around the batter in several concentric circles, going almost down to the bottom of the pan. (Don’t overdo the marbling!) With the back of a large spoon, push batter slightly higher onto pan edges and tube, leaving a “trench” in the middle.
- Bake for 75 to 85 minutes. Turn pan back-to-front once about halfway through baking time. If top of cake begins to brown, cover loosely with aluminum foil. Cake is done when a toothpick inserted into the middle of the cake emerges with a few moist crumbs still clinging to it.
- Remove to cooling rack; allow to stand 15-20 minutes. Carefully loosen cake from the pan and tube; invert onto another cooling rack; re-invert to cool right side up. When completely cool, store airtight. Allow to stand at least overnight before serving.
Equipment needed: Measuring cups and spoons, Tube pan (10x4 in.), Wax paper, Whisk, Electric mixer with large bowl, Rubber spatula, Fine-gauge grater, Large spoon, Knife (flatware).