I'm a postpartum nurse and we handle milk like a delicate food.
Thaw in the fridge or under cool running water first so the warmer only has to nudge it up. In the warmer go for the lowest heat and take pauses to swirl rather than shake so the fat and heat distribute evenly. If your unit runs hot heat the bath water then switch the power off and let the that model sit in that gentle bath while you swirl every minute. Finish as soon as it feels lukewarm on your wrist and never use a microwave.
