I do a vege dish that everyone here likes.
broccoli
cauliflower
zucchini
red pepper
yellow pepper
green pepper
mushrooms
Cut into thinnish wedges and place in baking dish. Add 1 tin of washed red kidney beans and smother in cheese sauce. Cover that in a thick layer of breadcrumbs and then a mix of sunflower and pumpkin seeds. Bake until cooked (I make it - I don't time it). For the cheese sauce I find a mix of Edam, mozzarella and Parmesan (fresh) is best.
It should come out like a unlayered lasagna. It's filling and non-meat. You can substitute any veges you want, but that mix is the best I have found so far.
You are screwed if they are vegan though.