3 Eggs, room temperature
1 cup sifted all-purpose Flour
1 Tablespoon Baking powder
3/4 cup granulated White Sugar
3/4 cup unsalted Butter / Margarine
2-3 Tablespoon Cocoa Powder
1. Soft or partially melt Butter. Cream sugar and Butter with the help of egg beater until light and fluffy.
2. Add egg one after another and beat well.
3. Combine flour and baking powder.
4. Gradually add the dry ingredients and beat well after every installment.
5. Divide the batter into two equal parts. In one bowl add the cocoa powder and mix.
6. Take a cake mold and alternative pour both white & chocolate mixture into the center, creating a small circle. Repeat until all the mixture is used.
6. Put the mold in pre-heated oven for 10-20 minutes (depending upon oven).
7. Check regularly by insert toothpick or knife in center, if material come with it, then it needs more time.
Experiment (Little variation for Marble Cake)
1. Don’t divide the batter into two parts. Add only 1 Tablespoon coca powder in batter at one side.
2. Using your finger or wooden spoon, gently draw swirls through the batter to marbleize it.
3. Milk can be also used in both recipes, if needed.
http://www.marthastewart.com/339716/marble-cake (Another recipe OR Variation of Marble Cake)