I found this bar at Whole Foods. I had heard of Mast Brothers chocolates but I had never tried any of their bars.
This was a very unusual bar. It tasted much darker than its 60% cacao would imply, but that was probably the coffee flavor making it seem deeper. But there was an aftertaste of something tangy, and I checked the ingredients to find “buttermilk powder”. That explains it. And I suppose this ingredient makes this bar a milk chocolate bar. I liked it though, and so did my co-workers. It disappeared quickly.
BTW, a quick check online showed that the beans in the bar are sourced from Tanzania. I find it odd that they would leave off the single-origin nature of this bar from the label, but it doesn’t mention the bean origin anywhere. Oh well. I got a couple more bars from this brand, so I will try those out too!