Preheat your oven to 180 degrees celsius (fan-forced) and line a 20cm round baking tin with baking paper. Set aside until needed.
Place the butter and caster sugar into your Thermomix bowl and mix for 30 seconds, Speed 3. Scrape down the sides of the bowl and mix for a further 20 seconds, Speed 3.
Add the vanilla extract, milk, eggs and self raising flour and mix for 10 seconds, Speed 4.
Scrape down the sides of the bowl and mix for a further 5 seconds, Speed 4 or until well combined.
Transfer the mixture in three equal parts (approx 180g each) and add the cocoa to one and a couple of drops of pink food colouring (or cochineal if using) to the other. Mix to create the coloured mixture.
Add spoonfuls of the three different coloured mixtures to your prepared loaf tin and once all the mixture is in the tin, use a butter knife to gently swirl the mixture to create the ‘marble’ effect.
Place the cake tin into the oven and cook for 30 – 35 minutes or until your marble cake is cooked through when tested with a skewer.
Cool in tin for 5 minutes before transferring to a wire rack to cool completely.
Store in an airtight container or freeze indivually wrapped slices in the freeer for up to 3 months.
Notes
You will need to use softened butter for this recipe.
If you don't have any pink food colouring, different colours can be used or you can divide the mixture into two and have one chocolate and one vanilla.
You can create as much or little swirl as you like, use us butter knife to mix the batter to create this effect.
This Marble Cake can be baked in different sized cake tins, please note the baking time will vary.
To freeze, wrap in cling wrap or place in a freezer safe container and store for up to two months.
I usually ice this Thermomix Marble Cake with a simple chocolate icing however you can also top it with a store bought chocolate or vanilla icing, and it's even delicious served un-iced.