I don't know how healthy this all is necessarily, but they're all easily adjusted for just about any diet (though we are not fans of non-dairy cheese, and don't use it) freeze and bake well and we all like to eat them! And they all go into 9x13 pans.
Mexican Chicken Casserole - 1 can of cream of mushroom and 1 can of cream of chicken soup (health food stores have healthier options of these); small can of mild green chiles; 24 oz of cooked chicken (though you could probably go up to 36 oz if you wanted extra protein... and post-partum I plan to do just that - shredded or chopped up into bite-size pieces); 16 oz of grated cheese (whatever kind you like with your Mexican food, I typically mix colby and pepper jack, but may say no to peppers post-partum til I get a better idea of how sensitive Baby is); one-pound size bag of your favorite corn chips; optional medium onion - chopped; optional mushrooms - chopped and as much as you care or don't care to consume; optiona bag of baby spinach.
I saute the onions, mushrooms and spinach, then set them aside to let them drain as much as possible. Then I mix the soup, chiles, chicken, onion, mushrooms, and spinach in a good-sized mixing bowl. Get out the pan, use non-stick spray or wipe it down with olive oil, then put a layer of corn chips in the bottom. Add a layer (it won't be completely covered - I try to glob it on there evenly) of the soup mix. Then a layer of grated cheese. Repeat that, using the rest of the soup mix and cheese but not necessarily the chips. Cover with foil and freeze. Baking is 350 for 30-45 minutes depending on your oven, and you can uncover it the last 5 minutes or so to toast up the cheese. Since everything is cooked, you're just getting it good and melty. :) It's a lot like less-labor intensive chicken enchiladas, it's a great way to get my kids to eat spinach, and I usually eat it with sour cream and/or salsa. I think you could - but haven't tried it myself - easily substitute ground beef or turkey if you prefer.
My lasagna is nothing fancy, I follow a basic recipe off a pasta box, and this is just how I adjust it for us: We usually use ground turkey, we always use rice noodles (Tinkyada is a happy gluten free option we like - brown rice pasta that doesn't turn to mush) (my ds is mostly wheat free on a rotation diet so we avoid it when we can), and I add sauted spinach, onions and mushrooms to almost everything I eat, lol, so I mix it into the cheesy stuff, which in our family is half-cottage cheese, half-ricotta, a good half cup of parmesan and a couple of eggs. And I saute some fresh garlic too for this dish, and use my store-bought pasta sauce. It also freezes well, and cooks essentially the same as the Mexican Chicken, but it can take closer to an hour to get it cooked through... I'm still getting used to this oven, and I may be getting used to a different one by the time the baby comes.
Baked Spaghetti - I take a pound of rice spaghetti (Tinkyada again), cook it and blend it with 8 oz of ricotta cheese - sometimes more or less depending on what I have left from lasagna, (I usually make them both and freeze one for later because my local store only sells an enormous tub of ricotta!) half cup of parmesan and two eggs. Then I sort of smash it into the pan like a really thick pie crust. I saute the onion, mushroom, and spinach I add to everything. I brown a pound of ground beef or turkey, mix it with whatever ricotta, parmesan or cottage cheese I may have left - mozza if nothing else - add the veggies (you could so easily and happily use zucchini or squash or both instead) and put it in like the pasta "pie crust" filling. Then pour as much sauce as I feel like using (typically the whole jar) all over the top of that. Cover that with grated mozzarella, and again with 350 for about 45 minutes.
The spaghetti and lasagna are a bit repetitive if you're not into that kind of food, but happily my kids and dh are! I will definitely do at least one of each of these. REALLY hoping I'll find my slow cooker in storage before May. My dh is only home a couple of nights a week so these last us a couple of nights usually. And I'm hoping I can get dh to make us some soups when he's here. He's the soup maker around these parts.
I really like the zucchini instead of noodles idea for lasagna - I will definitely try that. Now I need to check out savingdinner.com, too. And simple things like tuna or chicken salad hadn't even occurred to me! I will definitely make some of that with and with out eggs (ds can't have them).