The paragraph below is cited from November 10th, starting at 9:39. Here is the transcript.
Some might say it looks a little un-oven, or that its expression's a little frosty. But it's a cake artist's bread and butter and there's no getting a round the fact that it's one sweet sculpture, no ifs, pans or butter about it. This is CNN STUDENT NEWS where puns are a piece of cake.
I don't get the pun. (I've checked the dictionary, still don't get it.)
Please explain it to me, thank you.