Question: I'm going to the Elemental Plane of Fire, and I don't want my ice cream to melt. What's the least expensive and most portable method to keep my ice cream consistently intact?

Answer: 
Use the most powerful spell in the history of Pathfinder!

[**Prestidigitation!**](http://paizo.com/pathfinderRPG/prd/coreRulebook/spells/prestidigitation.html)

That spell allows you to chill 1 pound of non-living material.

If your GM allows it, using the custom magic item rules, you could make a box which would be permanently affected by the prestidigitation spell for as much as 1000 GP!

Prestidigitation would then be a permanent effect chilling the inner part of the "fridge" allowing it to chill all of the box's contents!
**Brown mold in an unbreakable container**

[Brown Mold](http://www.d20pfsrd.com/gamemastering/traps-hazards-and-special-terrains/hazards/special-hazards/brown-mold-cr-2/) removes heat, so use it to shield your ice cream. 

Your only challenge is to put it in a container that won't rupture when the mold tries to grow uncontrollably on the elemental plane of fire.