Why did my hot chocolate stink?

So I ran across a recipe for “crock pot hot chocolate”.

For those of you who are curious it is:

• 1.5 cups of heavy cream
• 1 can sweetened condensed milk
• 2 cups of vanilla chocolate chips
• 6 cups of milk
• 1 tsp vanilla extract

I don’t have a crock pot so I did this in a spaghetti pot. The only thing I did differently is that I used a smaller saucepan to melt the chocolate chips, using the sweetened condensed milk to hydrate it. This just made things easier. Afterwards I simply stirred and waited for it to get to about 70 degrees Celsius.

I was careful to scrape the bottom and sides of the pan as I stirred, although mostly during the beginning part when the chocolate was just added in. Later on I would leave it alone for maybe about a minute at a time but I would immediately stir to get rid of the film that had formed.

The hot chocolate was fantastic! Like a HUGE hit! However I am worried very much about something. There was this smell that I noticed occasionally while cooking. I had assumed it was just something on the burners, maybe even something from the recipe.

However, later on I let the remaining drink cool and was pouring it down the garbage disposal and the smell was back. It was really bad and very strong. I have no clue why! A friend had earlier smelled the chocolate after it was cooling and said he noticed the same thing.

What was the smell from? Do any of the ingredients I use smell particularly noticeable when burnt? Can burning a small amount account for the strong smell that was produced when the remainder was poured into the drain?

I really wish I could describe the smell but I really can't relate it to anything. It certainly wasn’t a rotten smell but it was bad and very strong.