Freezer cooking is a concept that's been around for many years; my mother did it in a simple form all through my childhood. These days, it goes by several fancy names, probably trademarked so I won't use them. But this is as much an idea in efficiency as in thrift. It's particularly useful for singles, couples, and small families whose time for cooking from scratch is very limited, but large families can find it useful too. It starts with the idea that that freezer connected to your refrigerator is useful for more than storing ice cream and commercial frozen dinners. Remember from earlier posts, too, safe food handling!
At the simplest, and for those with very limited space, I recommend cooking meat in bulk, dividing it into meal-sized portions and freezing those portions for future meals (preferably on your weekend when you have a little more time). When hams go on sale for the holidays, for instance, buy 2 and bake them at the same time (if your oven is big enough). It takes about the same energy to cook two in the oven at once, saving money there. If you make these on the holiday, I recommend cutting the meat not intended for the holiday dinner off in chunks to refrigerate because you'll probably be pretty tired by then. The next day, take out these chunks and either slice them for sandwiches or dice them into cubes and freeze in one or two meal portions. Recruit family to help, but make it fun (cooking should be GOOD family time, not drudgery.)
A week or two after the holiday, when you come home from work tired and late and need a quick dinner, pull out one of these packages, thaw in the microwave, and make a chef salad, hot sandwiches, shepherd's pie with canned biscuits as topping, an omelet with ham and tomato (or whatever you like), and so on. The idea here is that the meat itself is already cooked and ready to go. I usually pull down a package of meat the night before and put it in the refrigerator to thaw so it's ready by suppertime. (Remember SAFE thawing, not on the counter at room temperature.)
You can do this with those big chubs of ground meat, roasts, chickens, turkeys, bags of chicken leg quarters, etc. Having the meat pre-cooked or browned means you save that time (and extra pan sometimes) when it's time to make dinner.