this recipe and just added a bit more rice, corn, extra cumin, and diced jalapeno peppers. You could also substitute can tomatoes for salsa.
Saute in a skillet a chopped onion and some garlic. Add a chopped green pepper and as many chopped mushrooms as you'd like. Add 1/2 cup water and 1 cup rice and bring to a simmer. In a casserole dish, stir together 1 can diced tomatoes, 1 can beans (kidney or black), and a can of corn (or frozen). I also added some chili powder and a ton of cumin plus salt and pepper. Stir this together and then dump in the rice mixture from the skillet and stir the works together with 1/2 cup grated mozzarella cheese (skim if you prefer). Top the whole thing off with up to another 1/2 cup of cheese. Bake 15-20 mins.
For variations, add other veggies (maybe peas?) chicken, salsa or another type of cheese.
It was great and made for awesome leftovers and served with tortilla chips.