Pour one cup of water into an Instant Pot. (It is very important that the sealing ring be completely clean and odor-free or your dulce de leche will end up tasting like the last meal you prepared in the Instant Pot.)
Pour the can of sweetened condensed milk into a stainless steel or oven-safe bowl that will fit inside of the Instant Pot.
Cover the bowl tightly with aluminum foil. This prevents condensation that results from pressure cooking from ruining the dulce de leche.
Place the bowl inside of the water bath in the Instant Pot.
Close the Instant Pot, set it to sealing, and pressure cook at high pressure for 90 minutes.
When finished, perform a natural release and carefully remove the hot bowl from the Instant Pot and remove the aluminum foil.
Use an immersion blender to blend the dulce de leche until it reaches a smooth consistency. Note that it will thicken as it cools.
To store, cool and pour into airtight containers and refrigerate for up to a month or freeze for several months.