Pour sweetened condensed milk in a canning jar. Cover with aluminum foil. Add a trivet in the Instant Pot inner pot. Place the jar on top. Fill with water just until it reaches ½ inch below the top of the jar. Close the lid.
Cook on Manual/Pressure Cook (high) for 40 minutes, followed by a quick release of the pressure. (Add 5 minutes if you want a darker brown color, or reduce 5 minutes for a light golden brown color)
Using a kitchen towel or potholder, carefully remove jars as they are hot. Remove the foil. The condensed milk will probably look curdled at this point, but that's normal.
Stir it for 30 seconds, until it becomes creamy and smooth. Store in an aitfight container in the refrigerator.
Optional Add-on:
Sprinkle in a pinch of sea salt and stir well. Salt enhances the caramel flavor of this sauce.
Notes
Note: The nutrition facts below are my estimates. If you are following any diet plan, I recommend cross-checking with your preferred nutrition calculator.