A luscious, moist cake that beautifully swirls together vanilla and chocolate batters in one delicious treat.
- Place the butter and 400 g of caster sugar into the bowl of a stand mixer fitted with a paddle attachment. Beat on speed 6 for 3 minutes until light and fluffy.
- Reduce to speed 2 and add the eggs, one at a time. Add the flour, baking powder, salt, vanilla, and milk. Mix on speed 2 until just combined.
- Divide the batter evenly between two bowls.
- In a medium bowl, mix the remaining 50 g of sugar, cocoa powder, and water until smooth. Add this chocolate mixture to one bowl of batter and gently mix on speed 1 until well combined.
- Spoon a scoop of vanilla batter into the base of a prepared cake tin.
- Add a spoonful of chocolate batter on top, pressing down slightly to leave some vanilla visible.
- Repeat the layering until the tin is filled about three-quarters full.
- Bake in a preheated oven at 175 °C for 50 minutes.