The frozen hot chocolate is one of those things you have to try, just to say that you tried it. It was a warm day outside and I decided that I HAD to try the frozen hot chocolate and fulfill my list of things to do before I left Vegas (trying THIS drink was one of the things on my list). I'm glad I did, because now I know. After reading Yelp reviews about this place, I realized that I did not have time and money to waste to dine in, so I ordered a frozen hot chocolate at their To Go window located in the back (other side not facing the main street). I believe it was around $8.50 (?) for a regular sized cup that looked like a grande chocolate chip frapp from Starbucks. I'll have to admit that it did taste pretty refreshing and similar to a chocolate frosty from Wendys with whipped cream and chocolate chips like frapps at Starbucks (price difference exerts Vegas lifestyle). I liked it, but would not go out of my way to get this again. At least I left Vegas happy, because I finally tried a frozen hot chocolate that everyone raved about at Serendipity's.
P.S. To Go window does not have as many things that you can order compared to their regular menu, but it's faster if you are on a time crunch.