2 cups plus 2 tablespoons all-purpose flour
1/2 teaspoon salt
2 teaspoons double-acting baking powder
1/4 teaspoon mace
3/4 cup (1 1/2 sticks) butter or margarine, room temperature
1 1/2 cups sugar
4 eggs, room temperature
1 teaspoon vanilla extract
1/2 cup milk
1/4 cup unsweetened cocoa powder, sifted
Preheat the oven to 325 degrees F.
Grease and flour a 9-by-5-by-3-inch loaf pan, using the 2 tablespoons of flour, shaking out the excess flour.
Sift the remaining 2 cups of flour with the salt, baking powder, and mace.
In a bowl, using an electric mixer, cream the butter or margarine, adding sugar gradually. Cream until very light.
Add the eggs, one at a time, incorporating one before adding the next.
Mix the vanilla into the milk and add it alternately with the flour mixture to the creamed mixture. Stir only until blended.
Divide the batter in half and fold the cocoa into one half.
Carefully place the chocolate batter in one side (lengthwise) of the pan and the plain batter in the other side.
Bake for 1 hour. Cool on a wire rack, removing the cake from the pan after about 10 minutes.