Method

Preheat oven to 180°C and grease a 20cm cake pan with melted butter.

Use an electric beater to mix the butter, sugar and vanilla essence in a medium bowl until creamy.

Add the eggs in one at a time, beating well after each addition until combined.

Fold the flour mixture into the butter mixture and then add the milk gradually.

Divide cake batter into two even portions. Stir cocoa powder into one portion and mix well.

Transfer plain batter into the greased cake pan and tap it lightly to distribute the batter evenly.

Pour the chocolate batter on top of the plain batter and lightly swirl with a butter knife to create a marbled effect.

Bake for 45-50 minutes until golden brown or until a skewer inserted into the centre
comes out clean.

Remove from oven and set aside in pan for about 5 minutes. Turn onto a wire rack to cool completely and serve.