I like to make big pots of Chicken soup. I make sure that the chicken I put in has the skin and the bones - it adds richness, fat and flavor. I don't skimp on the veggies (I hate eating raw celery but loooove it in soup! and almost always put zuchini into soup) and often add lentils instead of noodles or rice. Very very filling! Especially if you eat it with a nice hearty roll and a little parmesan cheese.

Chili is another option that can be made up and frozen ahead. Or lasagne. Or Tuna Noodle Casserole. Or....

I live alone but I virtually never cook for one. I'll make gigantic casseroles and put up most of it, or cook a decent sized roast and have sandwiches for a week. Or same for a bone-in ham, and then I can make soup with the bone. I just wish I had TIME to do more of this sort of stuff....