how long will milk-based hot chocolate last?

[Anonymous]

I'm planning to do a hot chocolate bar for our upcoming daytime holiday party. I think milk-based cocoa tastes the best, so I'd like to use that, but I'm worried about it spoiling. I bought a cheap coffee urn for this purpose and was thinking I would make the cocoa on the stove top and transfer it to the urn to keep it hot & for easy dispensing. Any thoughts on how long the cocoa will be good? If you think this is just a terrible idea, any good recipes for hot chocolate without milk?