K.R.
Hi, L. -
I have a 5 year old and twin girls, 2. From the time that they were each about 1, they have all loved,loved, loved, Nancy's Quiche Florentine. You can cook them up in the microwave in less than 3 minutes, cube them up and they're ready to go. The kids get protein from the eggs and cheese and a pretty good serving of spinach, too. I serve them with applesauce. The other thing my toddlers have all loved is what we just call "cold lunch". I have the deli cut me a really thick slice of turkey, ham, roast beef - whatever they prefer - and cube it up. Give the kids a plate with cubes of meat, cheese, fruit, crackers, avocado - whatever. They love that, too. There's always ever-lovin' mac & cheese. Michelina's makes a frozen one called Wheels & Cheese that my kids love because of the shape, and I serve it with broccoli. Some of their other favorites are Campbell's Mega Noodle Soup, and hot dogs and beans. Have you tried your son on baked beans? They're full of protein and pretty sweet, so he might like them.
Good luck. It's always so hard. I'll be reading the replies to your post to get new ideas for myself, too!