Combine the sweetened condensed milk, vanilla extract and cocoa powder in the bowl of your slow cooker. Use a whisk to combine and make sure the cocoa powder is fully incorporated and smooth.
Add the remaining ingredients and whisk to combine.
Cover and cook on LOW heat for 2 hours, stirring occasionally to make sure the chocolate is melting into the drink mix.
Once the chocolate is melted through, and the drink mix is warm, you can enjoy! Keep the slow cooker on "warm" setting and stir occasionally to prevent a film from collecting on the top layer of the hot chocolate while serving.
Notes
Easily serve your hot chocolate with a drink ladle. Top with whipped cream, mini marshmallows, peppermint chips or a drizzle of chocolate syrup or caramel to make it extra fun!MAKE AHEAD & STORAGE: You can make this hot chocolate ahead of time, bring to room temperature and then store in air tight containers in the fridge for up to 7 days. I like to store them in multiple large mason jars, for easy reheating.
You can also prepare this hot chocolate on the stove top and then transfer the mixture to the slow cooker when it's combined.