Make the ice cream base as recipe directs. Make sure it is ready to either go into a churner or the freezer.
Either leave the batter in the Thermomix or return it to the Thermomix if it has been in the fridge overnight or whatever. Add the flavouring and blend 10 sec/speed 10. Taste and adjust if you think it needs it. Remember once frozen, some of the flavour is lessened.
Divide mixture into 3 parts. Stir through the pink and blue colours leaving the 3rd part white.
I used my churners to churn the pink, blue and white separately. I dolloped mounds of soft serve consistency ice cream into the container and didn't stir them at all.
When you scoop the ice cream it will look as you hope, though you could use a skewer or similar to swirl a pattern whilst the mix is still not completely frozen.
Alternatively you can semi freeze each colour separately and then combine them with a quick fold in one container when they are well on their way to freezing.