When out in the wilderness, be it by choice or because the SHTF and the grid collapsed, at some point you are going to long for a nice, warm meal. Ideally you will have food items on hand that you socked away or foraged to acquire. Having access to an iron skillet is extremely useful as iron skillets are very versatile when it comes to preparing food. If you have food to cook and something in which to cook it, all that remains is a heat source.
Building a camp fire is effective for cooking, but sticks and tree limbs make for an uneven surface. This sets you up for spillage of precious food that you may not have to waste. You could suspend your food over the fire by hand or by using an improvised skewer, but you can only hold so much for so long, and food preparation takes time. It would be best for you if a flat cooking surface were present to take the pressure off of your hands as well as preventing you from getting burned.
The best and easiest way to give yourself a level cooking surface is to find a portion of tree trunk over which to cook. You can get this by cutting a tree yourself or finding a downed tree and removing a section. Once you have secured a portion of tree truck, preferably about 36 inches tall, you will need to cut into it but not through it. Your goal is to make slits in the trunk for heat to smolder. With a chain or manual saw, cut into your trunk like you would a pie, creating between 6-8 even sections. Do not cut all the way through your log. Cut between one half to one third of the length of the trunk as you want it to stay intact at the base. In the openings you have cut between each section, stuff kindling or newspaper and ignite. This will cause the trunk itself to start burning from the inside out, creating a heat source on which you can prepare your meals.
Place your skillet filled with deliciousness on top of your log and prepare as usual. Be mindful that your temperature cannot be controlled as easily as that of a stove, so you will have to compensate for differences in heat so you do not undercook or burn your meals. Also be aware that this can burn for quite some time so you will need to douse it thoroughly when finished. While not the most ideal option for food preparation due to the tools required to make it happen, it is definitely something that can be done with the proper provisions, all of which you should plan to have access to in a survival situation.