In the bottom of your slow cooker, combine milk, sweetened condensed milk, chocolate chips, heavy whipping cream, and vanilla extract (I used a large wooden spoon).
Place lid on slow cooker and cook on low heat for about 2 hours, stirring every 30 minutes or so (I actually used a whisk to stir it to help make it smooth).
It’s ready to drink when the chocolate chips are completely melted and the hot chocolate is smooth.
Once it’s finished cooking, switch the heat on the slow cooker to “keep warm” and this hot chocolate is good for a few hours. I kept mine on warm for almost 5 hours during the day and people kept coming back to get more! You will just want to be sure to give it a good stir/whisk every 45 minutes or so.
Notes
Feel free to use semi-sweet chocolate chips for a richer hot chocolate. Any kind of milk will work. Recipe adapted from AllRecipes.