I did some modifications on the recipe. For instance, I used normal flour instead of the cake flower mentioned in the recipe. Also, I replaced the water with low-fat milk. In my opinion, the milk makes the cake softer.
The cake turned out good after 50 minutes of baking in a 300F oven. The not-so-fancy oven in my apartment doesn't seem to be intelligent enough to keep the temperature stable. I had to monitor the baking process to make sure the cake was not overcooked (or burnt).
Here is the recipe that I used:
2 cups sugar, divided
1 1/2 cups cake flour
2/3 cup unsweetened cocoa powder
2 teaspoons baking powder
1 teaspoon salt
1/2 teaspoon baking soda
1/2 cup vegetable oil
7 eggs, separated and at room temperature
3/4 cup low fat milk.
2 teaspoons vanilla extract
1/2 teaspoon cream of tartar
1. Heat oven to 325°F (160° C).
2. Combine 1-3/4 cups sugar, flour, cocoa, baking powder, salt and baking soda in large bowl. Add oil, egg yolks, water and vanilla; beat until smooth.
3. Beat egg whites and cream of tartar in extra-large bowl until soft peaks form. Gradually add remaining 1/4 cup sugar, beating until stiff peaks form. Gradually pour chocolate batter over beaten egg whites, folding with rubber spatula just until blended. Pour into an ungreased 10-inch tube pan.
4. Bake 1 hour and 20 minutes or until top springs back when touched lightly. Invert pan on heat-proof funnel until completely cool. Remove cake from pan; invert onto serving plate.
Makes 12-16 servings.