Pour the sweetened condensed milk into a pint-sized mason jar and secure a lid loosely.
Place a trivet inside your Instant Pot and place the jar on top, situated in the center so it is sturdy.
Pour water into the pot so that the top of the water sits where the sweetened condensed milk is.
Place cover on pot and set to sealing. Cook on high pressure (use the pressure cook button) for 18 minutes. Since there is a lot of liquid in the pot, it will take approximately 30 minutes before it comes to pressure. Don’t fret! It’s doing its job!
Do a 10-minute natural release, then vent remaining pressure.
When the silver float valve drops, remove the lid and carefully remove the jar from the pot using a hot pad holder. Remove lid and give the mixture a really good stir. Let cool to room temperature. Store in the fridge until ready to use.
When ready to use, heat in 30-second intervals in the microwave as needed.