In a medium heavy bottom saucepan, bring the milk to a simmer over medium heat.

Once it simmers, turn down the heat to medium-low and let it gently simmer for about 25 minutes, stirring the milk occasionally to make sure it's not getting scorched on the bottom of the pan. 

Simmer until it's reduced down to roughly 1 ½ -1 ¼ cups ( about 12 fl oz/360 ml) of liquid. 

Once the milk has reduced and turned a creamy color pass it through a sieve to remove any skin. Set aside to cool completely. 

Store the evaporated milk covered in the fridge for up to 5 days.