If too much flour is used, it can result in dry hard buns. Measure flour by gently sprinkling it into the measuring cup with a spoon, then swipe off any excess with a knife. Another culprit for hard buns: the dough was not sufficiently kneaded. If the gluten (protein in the flour) is not worked and stretched enough during kneading, the dough will not rise properly and the hot cross buns will be hard and dense.