Comment by danbruc
5 months ago
That is the correct answer. Also there is a lot of potential nuance, like evaporation or when you take the milk out of the fridge or the specific temperatures of everything, but under realistic settings adding the milk late will get you the colder coffee.
Does the ceramic mug become a factor? As in adding milk first allows the milk to absorb heat that otherwise would have been stored in the mug too quickly and then radiate back into the liquid over time slowing its cooling curve. (I have no idea btw I just enjoy trying to come up with gotchas)