Marble Butter Cake

Not enough chocolate powder.

This is the recipe:
Ingredients
250 gm butter
200 gm caster sugar
6 large eggs
1 tsp vanilla essence
300 gm self-raising flour (sifted)
½ to 3/4 cup of evaporated milk

Method
1. Preheat the oven to 160°C.
2. Beat the butter with the caster sugar until white and fluffy. Add in eggs one at a time and mix well. Then add is vanilla essence and evaporated milk and mix well.
3. Replace about 30g of flour with cocoa powder. After the flour is mixed into the butter mixture and mixed well, take out about 1/3 of the batter and add the cocoa powder into it. Place the white batter into tin and drop the chocolate batter into different spots and use a skewer or a chopstick to swirl it to make the marble effect and bake for about an hour.