Pour half of the sweetened condensed milk into each jar, add 1/2 of the vanilla bean paste into each jar. Stir to combine. Wipe rim of jar clean and seal with lid and ring.
Place in slow cooker and cover jars with water. Add enough water so there is at least 1" of water over the jars. You can lay the jars on their side if you need to. Set temperature to low. Cover slow cooker and cook for 8 to 10 hours.
Remove from slow cooker and place jars on a towel until cooled.
Serve and enjoy!
Notes
You can substitute 1 tablespoon vanilla extract or 1 vanilla bean for the vanilla bean paste. I cooked these for 8 hours to get this color. If you would like it richer colored, cook it longer. Note that at 10 hours it is as thick as custard. Recipe can be doubled and tripled to suit the size of your slow cooker. I usually cook 4 jars at a time.
If your slow cooker is shallow you can use wide mouth half pint jars.