Nutella. I must have gone through about 100 jars through university and finally OD'd on it. I still haven't recovered.

I used to hate peanut butter as a kid. But now I love it.

Oh, another one is those chocolate ice cups (you know, the kind you get at christmas and it "melts" in your mouth?). I couldn't get enough of them as a kid and out of nostalgia I bought a package of them a couple of years ago. I threw them out, they were WAY too sweet.