Vegetable soup.
Three leeks, or how many you have
four shredded carrots
three Knorr chicken stock cubes
liberal sprinkling of dried chilli flakes
Dried country vegetable soup mix
Variously add bits of chicken, shredded lettuce, courgettes, mushrooms, bits of potato and red pepper etc.
and try to get as much fluid in the pot as is humanly possible.
With a bit of dilution as the week progresses to stop me having to cut it out of the pot on days two or three, this pot with occasional additions feeds one for the best part of a week at four or five ladles full each day.
The pot isn't exactly a horn of plenty, but seems to perform that way.
I wouldn't recommend that you serve it to your guests as it's way too good for that - beeks only. Stored cold way and served warm way of course.
The OH won't touch it, which allows the chilli and occasionally an onion gets cooked in it mid week just for good measure and for me of course.
Tinned soup - doesn't last all week or use up spare veg.