String bean casserole is really good. Pumpkin/sweet potato casserole is good too. I don't have much experience with casserole dishes but I do have experience with someone who refuses to eat veggies. Below are some of the things I think most guys will eat even if they dislike veggies.

There are a lot more vegetables than that that you can try--fennel, bok choi, turnips...

Turnips can be mashed with mashed potatoes (he won't even know it's there). Fennel is absolutely delicious caramelized in a little olive oil with salt, pepper, and a splash of lemon juice. Will he eat asparagus? If he'll eat carrots, will he also eat parsnips (very similar, slightly stronger taste, but sweeter.) Will he eat sprouts? Water cress? Arugula? (Last three are amazing in sandwiches)

And are you sure he won't eat spinach? Not even in a cheesy dip? Or in fried dumplings (gyoza?) The dumplings get scarfed down by the aforementioned guy who refuses vegetables in any other form. He also loves fried dill and lamb dumplings.

Napa cabbage stewed with chinese lions head meatballs. (Not made with real lions.)
I know you said he won't eat peas but Snow peas sauteed with shrimp...

Or chicken lettuce wraps? Mirin, soy sauce, sesame oil, diced chicken, diced carrots, diced onion, water chestnuts, cracked pepper. With hoisin sauce?

Cucumbers? Great pickled for just a day in sugar, white vinegar, and crushed minced garlic.

Bell peppers? I stuff them with diced onion, goat cheese, and chopped tomatoes, drizzled in olive oil.

Also, forgot to add. In shell edamame beans. Tossed with a little butter, cracked salt, pepper, and garlic that had been sauteed in said butter. I cook for a bunch of guys on some nights and I can make a giant pot of it and it'll be gone.

Shredding the veggies is a great way to hide em. My mom used to do it and the stuff she made when we were kids tastes great. I hated zuchinni and just about any squash when I was a kid. It made me gag. Other than that I would eat anything. My mom's lasagna is awesome. I did not realize for years and years that it had zuchinni in it.

My dad hates mushrooms. My wife and I have served many dishes with mushrooms when my parents visit. I live telling dad after he complements the dish that he has been eating shrooms. }:)

If there is no allergy involved my stance is that the cook serves what they want to cook and everyone else can STFU and eat it and then clean the kitchen when the meal is over.

But that is just me.

Shredding or chopping the veggies into such small bits that they basically disintegrate when cooking is a great idea. I do that for DH, who is also VERY picky, when I make pot pie, and if you didn't see me put veggies in there you would never no, because there are no chunks! I just put them in the food processor and blend them until they are mush I would think that would work with cassseroles.

When DH and I got together (and for a while after), he was a VERY picky eater (hence why SD is the same way). He never wanted to try new foods and never wanted to eat any veggies, or anything healthy for that matter.

I just cooked what I wanted and he eventually started eating it. When he was hungry and that was what I made for dinner, he ate lol.

It sounds like he's a kid but that's the way it worked for me. Now he likes almost everything I made, including veggies!

Some of his favorites are : Chicken breast stuffed with spinach and swiss cheese, honey glazed carrots, zucchini/squash (especially on the grill), and green beans.

Ha ha I thought he was peeking at your daughters in the shower or something.

As a picky eater he's not likely to change any time soon. Recent studies show that some people are "super-tasters" and food that is mildly less than pleasant (but good for you) taste HORRIBLE to them.

Taste, like many senses fades with age and by the time he's eighty he might like zucchini.

By the way the spell check at this site works well but not in the title line. If you're unsure of a spelling for a word in the title just put it in the body of the Post and it'll tell you if its wrong.