Many brands of Greek yogurt suffer from being over- or under-sweetened with some unpleasant textures. Yopa! Authentic Greek Nonfat Yogurt manages to be both creamy and slightly tart in a good way. Packed on top of the cups is granola, which you can just tip into the milky mixture for a little crunch. Made from locally-sourced milk, flavors include strawberry, cherry, tart blueberry, and peach. Olympic gymnast Gabby Douglas graces some packages. Full story for BostonGlobe.com subscribers.