Preheat the oven to 425°F.
Pour the sweetened condensed milk into a deep-dish pie plate or heatproof baking dish.
Cover the dish tightly with aluminum foil.
Place the covered dish in a larger roasting pan.
Pour hot water into the roasting pan until it reaches about halfway up the sides of the smaller dish.
Carefully place the water bath in the oven and bake for about 90 minutes, or until the condensed milk is thick and deep golden brown.
Check the water level during cooking and carefully add more hot water if needed.
Remove the baking dish from the water bath and allow the dulce de leche to cool.
Whisk until smooth and creamy.
Serve warm or cool over ice cream, cheesecake, pancakes, fruit, yogurt, or your favorite dessert.