We were there on a Sunday in December. Carrot ginger soup was on the buffet but not the butternut squash soup. I asked our waitress if she could get any of the butternut squash soup and she did. But guess what - I liked the carrot ginger soup better! I pulled the recipe from the cooking section of the disboards and have made it twice already. I've learned that it does not really require heavy cream, 1/2 & 1/2 works better. Next time I may even try all milk for the cream portion and see how that works. Also, I will not use processed cheese for anything so I substituted finely shredded colby/munster mix and it melted just fine.
I don't think you can go wrong with whatever night you have your dinner at Boma. There is such a large variety of items, I'm sure that's why they have to rotate them. There would not be room for everything on the buffet.