Marble Butter Cake

Recipe from Nazrah's mother-in-law, Neni Rose, who apparently got it from Kak Aiton.
Yield 1 8-inch round 3-inch high cake in this preparation
Cooking time 1 hour Prep time 30 minutes 

Note: You may convert the cake to your available tin size or even bake them in 2 loaf pans. Baking time will vary, I'd checked mine at the 40 minute mark (earlier if using loaf pans). I used salted butter and salt in my cake and didn't find it too salty. The ratio of chocolate versus vanilla batter is really down to your own preference; however it will be easier to achieve a nice marble effect with more vanilla batter so the 3:1 ratio worked well for me. I use two mixers (a KA and a hand held) for this cake - if you only have one, I'd suggest whipping the egg whites by hand and lose some calories you'd gain from the cake in the process.

• 8 large eggs, separated
• 9 ounces castor sugar
• 12 ounces unsalted butter
• 9 ounces all purpose flour
• 1 1/2 teaspoons baking powder
• 1 1/2 teaspoons pure vanilla extract
• 2 tablespoons good quality cocoa powder
• 1/4 teaspoon salt

Preheat oven at 160°C (convection fan on) with a wire rack in the middle. Line an 8-inch round cake tin with parchment, butter and flour. Sift flour, baking powder and salt in a bowl. Set aside.

Cream butter in the bowl of a stand mixer fitted with the paddle attachment till light and fluffy. In a separate bowl, whisk the egg yolks with the sugar till light. Gradually add this into the butter and beat on medium speed till just incorporated. In a separate bowl, with a hand mixer, whisk the egg whites till stiff peaks form. With a spatula, fold in the meringue into the egg yolk mixture in 3-4 batches. Add in the dry ingredients gradually until just incorporated. 

Divide the batter into two, 3/4 in one batch and the rest in another bowl. Sieve cocoa powder over the lesser batch and fold to mix well. Pour batter into tin, alternating between the two mixtures, starting with the yellow batter and ending with the cocoa mixture. Rap pan on counter several times to eliminate air bubbles. With a long skewer, swirl around the batter to create the marble effect. Bake for 40-55 minutes or until a tester inserted into the middle of the cake come out clean.

Cool on wire rack completely before serving. Cake keeps at room temperature up to three days and can be frozen up to 3 months.

http://pickyin.blogspot.co.id/2011/10/marble-butter-cake.html