Bring all the ingredients together in a mixing bowl and beat until you have a smooth, well-combined batter. Divide the batter evenly between two portions.

Take one portion and stir in the cocoa powder along with the extra 50 ml (3 tbsp + 1 tsp) of milk. Mix until the chocolate batter is smooth and evenly blended.

Generously grease a Bundt pan with butter or oil. Spoon the plain and chocolate batters into the pan alternately, allowing the two batters to overlap and create that beautiful marbled effect.

Bake at 180°C (350°F) for approximately 40 to 45 minutes. To check that the cake is properly baked, insert a toothpick into the center. It should come out clean when the cake is ready.

Let the Bundt cake cool before slicing. Then serve and enjoy every tender, chocolate-swirled bite.