I cook oatmeal for my hens. They really like it and seem to give more eggs after getting it. One thing I'm doing that may be a bit 'off the wall' is add a tablespoon of black pepper to it while I cook it. They go absolutely crazy for the stuff. I have read that cayenne pepper is good for increasing egg production, but lacking that, the regular ground black is what they get.
I fix mine in the microwave. 1cup of oats to 2cups water or whatever liquid I use. I then add leftover food from the dinner table from the night before if it is not being used to prepare another meal. If I don't use leftover food to add to it then I add some scratch and mix it all up and throw it in their run.
i use the quick cooking oats with some water in the microwave for a minute. Ive put apple sauce in it, once some left over meatloaf, peaches. They love it but I only give before bed on really cold nights or first thing in the morning.