to make the buttermilk - 1/2 cup milk add 1/2 tablespoon of white vinegar and let stand for 5 minutes. Thumb Up Helpful (329)Rating: 5 stars These are the best blueberry muffins. This is the exact recipe that I have been using for years except that my recipe called for 1/2 cup milk instead of the 1/2 cup buttermilk. Really, really good. Lynn Thumb Up Helpful (84)Rating: 3 stars These were not "The Best" blueberry muffins and in fact I was a bit disappointed with these.