1-2teaspoonspure vanilla extract or vanilla paste, optional
31/2 pint each canning jars with lids and rings
Open the cans of sweetened condensed milk and portion them equally into the three canning jars. Wipe the tops and sides of the canning jars, if needed, in case any of the sweetened condensed milk spilled down the sides. Place a lid and ring on the canning jar and screw tightly to seal. Put the three canning jars in a slow cooker and cover with water by one inch. It doesn't matter whether the jars are laying on their side or standing up straight - do what works best for the size of slow cooker you have. Place the lid on the slow cooker and set to low for 8-9 hours, until the dulce de leche is deep golden brown. Carefully remove the jars from the hot water and let them cool. If desired, open the jars and stir in 1/2 - 1 teaspoon vanilla extract into each jar. Replace the lids and rings and store in the refrigerator. Supposedly it keeps in the refrigerator for up to a month - good luck getting it to last that long!
The dulce de leche can be warmed up on low heat in the microwave or on the stovetop in a pan of water to be drizzled over ice cream, used as dip for apples, spread over crepes etc. We also enjoy it cold or at room temperature for a spread on bananas, apples, sweet breads (like banana or zucchini). The options are endless!
Slow Cooker Temp: don't shorten the slow cooker time by setting the temperature to HIGH. I read several reviews over different blogs that said doing that resulted in a very burnt, disgusting mess. Cooking Time: also, slow cookers vary in temperature so you'll have to experiment a little with the actual time you cook your dulce de leche. Mine was perfect after exactly 8 1/2 hours but it might take up to 10 or as short as 8 to achieve the perfect dulce de leche.