Marble Sourcream Pound Cake

I have been wanting to bake a rich buttery cake before my delivery but it didn't materialise. Finally after delaying for soo long, I had no choice but to get my butt to the kitchen and baked this, simply because the tub of sourcream was expiring soon.

The original recipe was shared by an online friend quite sometime back and I made it into a marble version. It came out perfect.

Ingredients
8oz butter
2 1/2 C sugar (original is 3 cups, I still find 2 1/2 c still sweet. You may want to reduce to 2 - 2 1/4 c instead)
250g sour cream (original is 1 cup)
1/2 teaspoon baking soda
3 cups all-purpose flour
6 large eggs
1 tsp vanilla
2 heapful tbsp unsweetened cocoa powder

Method
1. Preheat oven to 170C
2. In a large mixing bowl, combine the butter and sugar and beat till fluffy
3. Add the sourcream and mix until well incorporated
4. Sift baking soda and flour together and add to the creamed mixture alternating with eggs, beating each egg 1 at a time
5. Add vanilla and scoop out about 1/4 of the batter
6. Sift cocoa powder into the 1/4 batter and mix till well incorporated
7. Pour the original and chocolate batter alternately into a greased and floured tube pan
9. Use a knife to swirl the cake batter
10.Bake for 1 hour 20 minutes or till skewer comes out clean