Whole Foods is your friend. That's the first thing.
Pasta is super easy. You can go with a straight marinara or add imitation ground beef to it. All the imitation ground meat products that are found in the refrigerated section of Whole Foods are useful, and the vast majority are vegan.
I don't know how Chelsea feels about tofu, but that's a classic.
Also try couscous. Boil water, stir in the couscous, take it off the heat, let it rest for five minutes, then fluff it with a fork. Way easier than mac and cheese. Add olive oil, sundried tomatoes, imitation chicken stock, soak saffron threads in the water -- there are a lot of choices.
Original Boca Burgers are vegan.
Portabella mushroom sandwiches on hearth bread with olive oil, garlic, basil, and vine-ripened tomatoes are great. Add olives if you're adventurous. In fact, portabella mushrooms in dishes can taste and feel just like meat, and can satisfy meat cravings.
Edamame -- soybeans in the pod -- are the easiest thing to make and can neuter a killer protein craving.
Dissolve 1 level scoop of Nutritional Yeast Flakes and 1 - 1½ teaspoons of Bragg Liquid Aminos in 8 ounces of boiling water for a rich, satisfying, salty-tasting broth containing 9 grams of protein. It tastes a bit like chicken broth. Both of these ingredients are useful in that they provide B12, which absolutely has to be supplemented in a vegan diet. (Really, regardless of what she's read to the contrary, it really, really does need to be supplemented. She'd be good for a couple of years with her body's stores, but then her body would stop working.)
Malt-o-meal, prepared with water or milk substitute, or the Asian hot cereal called BioLife are both good for breakfasts.
When out for dinner, salads, pasta, and baked potatoes with salsa are all options. Indian and Ethiopean foods are also frequently vegan.
For milk substitutes, either get Silk from the refrigerated section or Pacific-brand rice, grain, or nut milks from the unrefrigerated section. Generic soymilk is pretty nasty.
If she likes cheese, Joanne Stepaniak's The Uncheese Cookbook is worth the cover price.
Check back-issues of my veganism blog at
http://www.mcgees.org/veganismblog.shtml for some other hints and recipes.
Ask if you need more pointers.