Step 1

Combine milk and sweetener in a medium saucepan. Whisk stirring constantly to dissolve sweetener over medium heat.

Step 2

When the milk begins to steam, lower the temperature to as low as possible.

Step 3

Dip a straw into the milk and use a permanent marker to draw a line on the straw, just above where the milk hit.

Step 4

Allow milk to reduce to half in size from what it first was, periodically checking with the straw and stirring. This took approximately 2 hours and 30 minutes for me.

Step 5

When milk is reduced by half, remove from heat and whisk in butter and vanilla extract.

Step 6

Pour into a clean glass jar and allow to cool completely. Store in the refrigerator.