Marble Butter Cake

This is a recipe adapted from Bakericious' Marble Butter Cake  (which adapted from Mrs NgSK's famous butter cake).  I did not use the egg separation method as I was too lazy; and since I couldn't find any self-raising flour in the pantry, I used plain flour instead, but added baking powder into it. Much to my disappointment, the cake came out from the oven with cracks on top.  However, it still taste good - rich and buttery!

Ingredients:
230g butter, softened
120g caster sugar
4 eggs (200g without shells)
1 vanilla pod, scrape all the seeds out
200g plain flour
2 tsp baking powder
1/2 tsp salt
4 tbsp milk
1 tbsp dark cocoa powder

• Preheat oven to 170 deg C.  Grease and line a 7 inch square cake pan with baking paper.
• Sift flour, baking powder and salt.  Set aside.
• Cream butter, caster sugar and vanilla seeds in a mixing bowl until light and fluffy.
• Add eggs, one at a time, beating to combine.  
• Fold in sifted flour mixture, alternating with milk; beginning and ending with flour mixture.
• Remove 1/3 of the batter and mix in cocoa powder.
• Spoon the plain and cocoa batter into the prepared pan alternately and use a chopstick to swirl the batter.
• Bake for about 50 minutes or until a skewer inserted into the centre comes out clean.  Stand cake in the pan for 10 minutes before turning out onto a wire rack to cool.