Pour the milk in a medium non-stick saucepan. Place over medium heat and bring it to a gently simmer.
Set heat to medium-low, just enough to keep a gently simmer.
Stir occasionally and allow the milk to reduce for about half, it will takes about 30 minutes, you'll notice because besides from reducing, it will changes its color aswell as it's flavor to mid-sweet.
Strain the milk into a bowl or cup using a fine sieve. Allow to cool down while stirring from time to time to avoid from creating a skin on top.
Cover and store for up to 5 days in the fridge or use immediately.