Here's what I heard you say.
I cook large meals and my family doesn't eat it all so I want to cook more meals.
I suggest you make a plan that goes by serving sizes. If you look at other countries they use smaller plates, smaller servings, and we use their serving platters for our meals.
A serving on chicken is small, it will fit in the palm or your hand. How much larger is your serving of chicken?
A serving of a veggie is 1/4 cup for little ones and 1/2 cup for adults. If you are having 2 veggies that is NOT 1/4 or 1/2 cup of each, it is 1/2 or 1/4 cup total that is the serving. It does not hurt to have that extra serving of a veggie but it does need to be counted in.
I think if you are cooking for your family and they are not eating all of it then you could cook the same things but make a bit less of it.
I make hamburger helper on the weekends. It's our big splurge.
My hubby eats a lot and the kids will too if the HB Helper is one they like and haven't had in a while. Our Walmart is horrible about getting the spaghetti one. So if I cook that kind I know that I need to make 3 boxes of it. With a 2 lb package of meat. I never use the entire meat they say. They also like the Tomato Basil Penne'.
If I serve green beans with some garlic powder sprinkled on and a bit of butter then some garlic bread I have more food than they can eat.
So if I plan ahead and make the added stuff I can get by with only cooking 2 boxes of hb helper with 1 -1 1/2 lb of hb meat.
Reading up on serving sizes and using smaller plates could be the first step towards cooking less foods and getting their tummies used to the idea of smaller servings filling them up.
We eat the same way you do, kids eat breakfast at school, they also eat lunch there, then we do a high protein snack with some good complex carbohydrates so it will carry them over until dinner especially if it's going to be a late night at the gym.
Then we do dinner. I add an evening snack though. I think the kids need something at night if they ate earlier. If they ate at 7 then they probably don't need something big but if they ate at 5:30 then at bedtime it's been over 3 hours and they need a little something or they'll be up during the night grazing.