I just made the sourcream coffee cake recipe from Carole Walters' "Great Cakes" and it came out terrific. I made the richest one (there are 3 recipes), which included 2 sticks of butter, 1 1/3 cup of sour cream and superfine sugar. The cake was so notably tender that I am wondering whether the superfine sugar had anything to do with it (obviously all that butter and sour cream helped).
I noticed that virtually every cake recipe in the book uses superfine sugar instead of granulated sugar. Does this really make a difference? Should I be substituting superfine for granulated in other baked goods?