Place a bowl over a saucepan with about two inches of water.

Pour the milk into the bowl and turn the heat to medium/medium-low (you want a steady simmer).

Place the probe of a thermometer into the bowl of milk.

Heat the milk slowly to 165F/74C , whisking every couple of minutes.

Once 165F/74C has been reached, maintain the temperature for at least 15 seconds.

Remove the bowl of milk to an ice bath or sink full of cold water.

Whisk a couple times for the first five minutes to prevent a film from forming on the surface.

While the milk is cooling, return to your pot of hot water and turn the stove to medium/medium-high.

Place a mason jar in the saucepan, cover, and allow to steam for at least 30 seconds.

Repeat for remaining containers.

Place the mason jar lids in the hot water and boil for 30 seconds. Remove to cool.

If you have a larger container that will not fit, pour the boiling hot water into the container to sanitize.

Place containers on a towel and allow to cool.