Place maple syrup into the Thermomix bowl and set timer for 5 minutes/100°C/speed 3.
When you can hear the syrup is hot, (it makes a little protest noise) at around the 3-minute mark, add the butter one cube at a time through hole in lid, quickly replacing the MC between each addition. As you hear the butter incorporate, add the next piece until it is all in. Increase the speed to speed 5 for any remaining time on the clock.
Store in a glass jar in the fridge. Melt gently without boiling to reuse.