There are technically two separate shops, although they're housed in the same building. One shop carries various assortments of the squares, and also offers a limited beverage menu; the other side is the ice cream parlor, which only really sells ice cream treats (cones, sundaes, floats, etc). Either way, you should be able to find what you're looking for. I hope this helps!
I'm sure they'll have it there. And agree with what @dustin says
They carry almost everything there. I wouldn't be surprised if they do have it although I don't specifically recall seeing it when I was there
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