Strawberry and Chocolate Marble cake

I've always like marble cake because the cake looks lovely with the marble effect. This one is from a recipe book but I modified it a little by adding yoghurt. Somehow, I find the cake a little dry a day after baking. Maybe a little bit more yoghurt will help :)

Ingredients:
Butter (150gm)
Sugar (3/4 cup)
Egg (2)
Vanilla Essence (1 tsp)
Yoghurt + Milk (1/2 cup)
Self Raising Flour (1 2/3 cup)
Strawberry Emulco (1 ½ tsp)
Cocoa Powder (3 tsp)
Oil

Preheat oven at 175C.

Method:
1. Beat butter and sugar till light and fluffy.
2. Add in egg one by one and beat till combined.
3. Mix in vanilla essence and yoghurt-milk mixture.
4. Sift in self raising flour and mix till combined.
5. Divide the mixture into 2 portions.
6. Add strawberry emulco to one portion and cocoa powder to the other portion.
7. Grease a baking pan.
8. Pour the mixture alternately into the baking pan. Swirl with a chopstick to create marble effect.
9. Bake for 35min or until cooked.