Tasty GF cake! I modified one thing, due to severe allergy to apples. I substituted the apple sauce for baby food pureed carrots. They worked perfectly! One thing to note: if you have a coffee grinder, it would do a world of good to process the oats into 'flour'-UNLESS you want the texture of whole oats throughout the cake (the next time we make it, we will grind down the oats). We just topped our cake with Cool Whip, but the frosting does sound divine! THANKS!