Oatmeal. I'm not especially fond of it, though I've recently been experimenting with ways to doctor it up- but it's basically the easiest meal I can throw together with the best pay off in terms of feeling full. Bonus points for remaining edible (hell, the texture is even preferable sometimes if left to sit for a bit, more creamy) long after it's gone cold: I often struggle to finish food before it's congealed or otherwise become unappetizing after sitting out for awhile. It's kind of like kibble. Pour oats from bag, slop in water, eat. Only thing easier than that is eating individual ingredients in something I can halfheartedly tell myself is like 'deconstructed charcuterie,' but at least oatmeal feels like more of a proper meal and involves less squinting into the fridge light.