Marble cake ??

Ingredients:
- 2 cups all-purpose flour
- 2 teaspoons baking powder
- ½ teaspoon salt
- 1 cup sugar or castor sugar
- ½ cup butter, softened
- 2 eggs
- 1 teaspoon vanilla extract
- 1 cup milk
- 2 tablespoons unsweetened cocoa powder
Method:
Place flour, baking powder, salt, sugar, butter or margarine, eggs, vanilla, and milk into mixing bowl. Beat slowly to moisten, then beat with an electric mixer at medium speed for about 2 minutes until smooth. Reserve 3/4 cup batter; pour the remainder into a greased pan.
Stir cocoa into the 3/4 cup reserved batter. Drop by spoonfuls over top of white batter. Using a knife, swirl the cocoa batter into the white batter to incorporate it in a marble effect.
Bake in preheated oven for 30 to 35 minutes at 150C. ??
