Dairy Zone’s supplier of butter cake thought they would be able to keep up with demand.

But the vendor underestimated just how much Iowa State fairgoers love their ice cream — let alone how much they crave the frozen delights of the Dairy Zone , a beloved East Side fries-and-a-cone spot.

And the provider wholly misjudged the popularity of the Zone’s Butter Cow Tornado, a blended mix of thick vanilla ice cream, bits of butter cake and butterscotch syrup topped with an Instagram-perfect white chocolate cow sitting on a cloud of whipped cream. A treat that’s become so sought-after this year, the Zone’s ice cream trailer was temporarily retrofitted to support a sliding assembly line: scoop, drizzle, mix; scoop, drizzle, mix; scoop, drizzle, mix.

So by the end of the first weekend, well,

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