How to translate a baking recipe for box mixes for cast iron skillets? I recently purchased a skillet at the advice of a trusted friend. I have seen a number recipes for a lot of foods including baked goods. But, the recipes are all "from scratch". Now, I realize that this is probably the best way to go. But, I saw recipes for making chocolate chip cookies and brownies in a skillet in the oven (in Dorie Greenspan's cookie book). I have some box mixes at home. 

How can I modify the baking instructions for the box mixes for use in a cast iron skillet? Are there general guidelines for this? 

The only thing I could find after searching online was on the Jiffy Mix pages for using their various box mixes in a cast iron skillet.
I follow the directions on the package, with one modification: when preheating the oven, I preheat the skillet in there as well. 

I add the batter or dough to the warm skillet then bake. I use the baking time on the box as a reference, but monitor by eye toward the end. It usually is done within -5 to +3 minute range as listed on the box.

I've done this with Jiffy corn bread, cake mixes, brownie mixes, etc. Usually very good result. Sometimes the bottom crust is thicker, but the kids liked that. I've never had anything come out as a complete disaster.

Oh.. I also spray the pan with non-stick just before pouring the batter.