Combine all ingredients except vanilla extract in a pot over medium-high heat. Bring to a boil, whisking constantly. (Make sure the pot is big enough so the milk won’t spill over the sides when it boils.)
Turn heat down so the mixture is just barely boiling and cook for about two and a half to three hours until it turns a deep caramel color. Stir and scrape the bottom and side of the pan periodically to guarantee even cooking. Note that it will thicken as it cools.
Remove from the heat and whisk in vanilla extract.
Use an immersion blender if necessary to remove any lumps.
If you find that your dulce de leche is still too thin after cooling, make a slurry of 1/2 tablespoon cornstarch with 1 1/4 teaspoons milk. Bring the dulce de leche to a very slow boil over medium heat, whisk this slurry into the dulce de leche, and continue to boil slowly for five minutes before removing from heat and cooling.
To store, pour cooled dulce de leche into airtight containers and refrigerate for up to a month or freeze for several months.
Instant Pot Instructions
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.
Slow Cooker Instructions
Line your slow cooker with aluminum foil. This prevents the ceramic bowl from accumulating rust from the cooking process that is difficult to clean.
Remove the label from the can of sweetened condensed milk and place into the foil-lined slow cooker.
Fill the slow cooker with water, making sure to completely submerge the can of sweetened condensed milk. This can must remain covered with water during the cooking process.
Cook on low temperature for six to 10 hours, depending on how thick you want your resulting dulce de leche. After 6 hours, the slow cooker dulce de leche should have the consistency of caramel sauce. At this stage, it is great for pouring over ice cream or adding to coffee in the morning. After 10 hours, the dulce de leche should thicken to the point where you can spread it like a preserve.
When finished, remove the can from the slow cooker and allow to cool to room temperature before opening.
To store, pour into airtight containers and refrigerate for up to a month or freeze for several months.
The nutrition information shown is for the sweetened condensed milk methods and the time is for the slow cooker method.When using the slow cooker method, always wait for the can to cool before opening it! If you do not, the can may explode from the pressure change.With the stovetop method, trying using goat's milk instead of whole milk to make Mexican cajeta.