This is a simple coffeecake recipe that uses buttermilk for extra flavour. You should use fresh blueberries when they are available, but frozen will work too.
I just made this with my 8 year old daughter and it turned out to be fantastic... not too sweet but soft and fluffy, contrasted with the crunchy and sweet topping. I loved it! I was going to skip the topping, but I am glad I followed the recipe. - 08 Oct 2012
Because I've had a quart of buttermilk to make use of and have been making lots of "Buttermilk This and Thats," I've learned very quickly what an incredible, stark difference in moisture real, fresh buttermilk makes in batters! SO much better than using soured milk, or powdered buttermilk, and so much better than not being included at all (I offer the "Black Magic Cake" from this site as proof!) The crumb is soft, tender and moist, just as it is in this cake as well. This cake is not overly sweet, so I hope no reviewers will dock it for that - it is a coffeecake, after all, not a dessert cake, although for my tastes it's perfectly suited for dessert too! For those of you familiar with "Blueberry Buckle," either the butter or shortening version, this coffeecake is similar...but better because the cake is significantly more moist, fluffy and has a more delicate texture. The ingredients and preparation method are perfect as written, tho' those wanting more "spunk" could certainly add some cinnamon to the crumb topping, or swap out the blueberries for other berries, or even use a cinnamon swirl or fruit filling (peach sounds awesome to me)! The crumb topping is what it should be, somewhat crackly and buttery, not cloyingly sweet or greasy. This batter is so basic, and so good that I'll be including this recipe in my reference file. Once again I'm convinced that any batter-type recipe with buttermilk in its list of ingredients is worth giving a second glance to. - 21 Jan 2010 (Review from Allrecipes USA and Canada)
I haven't tried this recipe but in reading the reviews someone said the blueberries all sank to the bottom. To prevent this add the blueberries to the dry mixture and make sure they are well coated with the dry ingredients before adding the wet. This also works for raisins & nuts. - 25 Jun 2003 (Review from Allrecipes USA and Canada)