In your slow cooker, whisk sweetened condensed milk, heavy cream, whole milk and spices together until combined. Stir in chocolate and cinnamon sticks. Set to low and cook for 2-3 hours, whisking every hour or so. Once the chocolate is melted through, remove cinnamon sticks, whisk it well and serve. If not using immediately, set crockpot to warm until you are ready to serve.