Mix together all ingredients in a 12 inch skillet or wide 5 quart stock pot. Gently whisk the ingredients until the butter completely melts. (i like to cut the butter into cubes to help it melt faster)
Bring to a boil over medium heat. Stir frequently.WATCH CAREFULLY to avoid scorching or overflow
Reduce heat to medium low
Simmer for 15- 20 minutes or until milk has reduced by 50 percent and is thickened. Make sure to stir frequently
Remove from heat.Stir in 1/4 tsp vanilla if you want a little more flavor to the milk. Let cool in the pan until room temperature . The milk will thicken more as it cools.
Pour cooled milk into a mason jar or an airtight container. Let cool completely before using or storing. Store in the refrigerator for up to 1 week.
If milk becomes solid and does not combine after being refrigerated rinse the jar with the lid on under hot water just to get the chill off. Remove the lid and microwave on high about 10 seconds or until the milk had become liquid and is smooth and thick. Stir with a fork to make sure the milk is completely smooth