My account on Xbox live says that I haven't gotten the "Vanilla Crazy Cake" Achievement but I actually have completed the achievement and when I load up Portal and look at the achievements in the game it says I have completed it. Is there a way to get my Xbox live account to "see" the achievement? If not can I delete the achievement in the game and do it again to see if it gets "seen" by my live account?
Theoretically you should be able to clear Portal's local cache and then it will either have no achievements at all (locally -- Live will be fine) or pick up the ones from Live, I'm not sure how it works. But yeah, clearing the Portal data off your XBox's HDD should allow you to get the achievement again. I've never done this on XBox but I have done the equivalent on Steam.