Protein and fat is my solution. Caleb loves to make a scrambled egg. Heap of fat (butter, bacon grease, coconut oil), add the scrambled egg, cheese if they'll eat that and it typically fills them up for a couple hours. Other things we do is peanut butter and honey sandwiches; pasta with add-ins (meat, sauce, etc); tortillas with melted cheese (Caleb calls it pizza). I like keeping fruits and whole wheat stuff around for snacks. Logan is gobbling down halved grapes right now.
I think batch cooking can be your best friend. Banana bread, rolls, big pot of plain pasta, muffins, etc. Heh, I'll even hand out bacon strips to buy myself a few extra minutes to pull a meal together.
Oy... now Logan is on his third bowl of grapes! I hear you on the hollow legs.