I make a macaroni & cheese, but with squash puree totally dominating the cheese. Something like Martha's- http://tinyurl.com/6hxm73. But I add fresh sage to the squash and mix crushed ginger snaps with breadcrumbs & butter for the topping. Everyone loves it. I suppose you could lose the cheese & butter altogether or vegans but I've never tried it that way.

I make this eggplant gratin with feta, mint and kalamata olives quite a lot--it has converted many people who thought they didn't like eggplant. It can be treated as a main or a side. It is pretty too and can be served warm or at room temperature. I use more tomatoes. I put this in a 9x13 pan and put the veggie layers almost upright to get a generous pan.
http://www.finecooking.com/recipes/eggplant_tomato_gratin.aspx

Wow! Thanks everyone. Great answers and you've all helped me out on this pickle!

I like to make vegan minestrone when I have to accommodate different eating habits. You can still get a lot of richness without using bacon or chicken broth.

My basic recipe involves diced canned tomatoes, carrots, eggplant, celery, onion, lots of garlic, mushrooms, and some zuchinni (add this close to serving time so it doesn't get mushy. I also add white beans, vegetable broth, red wine, tomato paste, basil, oregano and a small pasta or israeli couscous.

It's not a traditional minestrone, but its perfect for winter and for large groups with varying degrees picky eaters. Try topping it with some pesto!

If you need a "main"/protein dish, any veg chili will do. I especially like a black bean and winter squash chili -- you can find many! Make it thick so it doesn't run all over the plate. If there's no cheese, I'll repeat the previous comments -- why make two?

Uhh that was 'bag' of sweet corn.

Is there a specific reason to have 2 completely different dishes?

If you just want to provide something tasty for the vegans and vegetarians present, prepare a large amount of a single vegan dish will satisfy both types of diets. I make a nice chile squash stew (see quick explanation below) or most Indian food can be made vegan by substituting a higher smoke point vegetable oil for the ghee in the cooking process.

~ 6 fresh poblano chiles
1 butternut squash peeled & cubed
1 large sweet onion, large dice
2 cloves garlic minced
1 large can diced tomatoes
1 back frozen sweet corn
1 T. ground chile powder (I prefer Ancho)
1 t. cumin
1-2 boxes veggie broth
Salt & pepper to taste

Blister, peel & cut peppers into 1/2" pieces
Saute onion over med heat in large heavy bottomed pot in a few Ts oil until lightly golden.
Add garlic for 1-2 minutes
Add squash stir & cook for several minutes
Add spices stir & cook for few more minutes
Add tomatoes, poblanos, corn & broth
Cook over low heat until squash is tender.

Easy and yummie.

I have to second the food52 mujaddara for your vegetarian dish. I've made it several times already--mostly with whatever I have in the house--and it is absolutely wonderful. If you use oil to saute the onions and serve the yogurt on the side, you have your vegetarian and vegan dishes all in one.

This vegan dip is wonderful:
http://www.food52.com/recipes/8086_pumpkin_spice_cashew_cheese

For a main dish, this is my favorite vegan casserole:
http://www.vegetariantimes.com/recipes/9974

For Vegetarian, here are some recent contest winners on Food52:
http://www.food52.com/recipes/8565_mujaddara_with_spiced_yogurt
http://www.food52.com/recipes/4661_smoky_minestrone_with_tortellini_and_parsley_or_basil_pesto
http://www.food52.com/recipes/2611_broccoli_rabe_potato_and_rosemary_pizza

There was a vegetarian side theme before Thanksgiving - LOADS of ideas!

http://www.food52.com/contests/187_your_best_vegetarian_holiday_side

I don't know if you need sides or entrees but this maple roasted butternut squash salad is a win win. Roasting the squash is the only time consuming aspect.

http://wp.me/p15ytG-ci