We designed the Stagg EKG kettle to be an incredibly efficient and effective water heater/boiler. The software and hardware are crafted to be sure you have the best experience possible with water!
For this very same reason, the kettle will have no clue what to do with milk and most likely burn it. Even if it's set at a lower temperature, the heating cycle will likely scald the milk. In other words, please don't use the Stagg EKG with milk or any other liquid than fresh, clean water.
We don't recommend milk in any quantity to the Stagg EKG. Doing so voids your warranty and is likely to not go as planned!