When you use heat to extract the water from sweetened condensed milk, the fat and sugar literally caramelize, which tastes as good as it sounds. But this may be the sweetest news you’ll ever hear: there are four ways to achieve this consistency: in the microwave, on the stovetop, in the oven or in a slow cooker. Try one method or try them all, then get ready to drizzle some caramel icing on vanilla ice cream, chocolate desserts and fruit sorbets.
Pour the sweetened condensed milk into a large, glass measuring cup. Sprinkle the milk with a little salt. Cover the cup with plastic wrap -- always a good idea with microwave cooking but especially with bubbling caramel. Cook on medium power for 2 minutes, stir with a whisk and then cook for another 3 minutes. Reduce the setting to medium-low and cook for about 10 minutes, stopping the microwave to stir every 2 minutes until the milk turns light brown.
Set up a double boiler and heat the sweetened condensed milk in a bowl on top. Sprinkle the milk with salt. Simmer on low heat for 45 minutes to 1 hour, stirring every 15 minutes, until the milk turns soft brown, smooth and creamy.
Create a double boiler effect for your oven with two baking dishes. Set your oven to 425 degrees. Pour the sweetened condensed milk into the smaller dish, add a pinch of salt and set the dish inside the larger dish. Fill the larger dish with boiling water and set both dishes in the oven. Cook the milk for 45 minutes to 1 hour, stirring every 15 minutes.
Turn your slow cooker to low. Pour the sweetened condensed milk into a tall, glass jar after adding a little salt. Cover it and set it inside your slow cooker. Use several jars if they’ll fit. Fill the slow cooker with boiling water so it comes up to at least the halfway mark of the jar. It should take about six hours for the milk to turn to caramel; you’ll be able to tell by the light-brown coloring and the thickness of the caramel as you twirl the jar.