Apparently, this is a Toronto thing – or at least, an “east-coast” thing (it Toronto on the east coast?).    From searching the Internet and looking at other blogs, it seems this is something special that we do here – nestle blueberries and sugar in a yeast bun – and a delicious thing it is indeed.  If we can’t be famous for our bagels (yuck), at the very least, we have excellent taste in blueberry yeast desserts.   I have always wanted to recreate my Bubby’s, but my mother’s are excellent as well… really, any are, as long as the blueberries aren’t grossly undercooked, as a few have been that I bought at Hermes, a local bakery.    Frankly, I use canned pie filling, but if you have a source for nice, fresh local berries, use those instead.  This would probably work with many kinds of berry, but I’m closed-minded and believe blueberry is the best and only kind.   I used to think it would work with any challah recipe, but that’s not true.  You need the richest, alm...