This is a recipe from Everyday Food with a few tips from making them several times. The original recipe yielded 6 jumbo sized cupcakes but I've always made a dozen standard size cupcakes. They get rave reviews and are perfect for baby showers and other parties. I have made the cakes ahead of time, frozen them, thawed them out the night before the party and then glazed them the day of so the glaze stays nice. I think they taste best with Meyer lemons, but they are great with any type of lemon really. I have always used the yogurt becuase I usually have it on hand and not buttermilk. I bet it would be just as yummy with the buttermilk.