As part of the Map Maker's Toolbox project I've created a firepit in which you can cook food forever. 
The basic functionality is simple and easy to re-use for any purpose.

To use it, simply open the schematic in MCEdit and place it anywhere you like. Then destroy the redstone block and replace it to start the setblock-clock the contraption runs off of.
So, if you're creating maps and would like to have a firepit where the player can relax and cook up some food, have at it. 
(In the video I refer to my Github repository which is an alternative place to download the schematics from.) 

A few important things: 

• Does NOT need to be inside the spawn chunks to work. 
  
• Can be placed as many times inside one world as you like.
  
• To work as intended, doFireTick and commandBlockOutput gamerules should be OFF.
  

Feel free to use this anywhere; there is no need to credit me unless you're doing something that focuses around the contraption itself such as creating a video about it.