Preheat oven to 350 F (175 C). Combine bell pepper, garlic, chicken broth and onion in a skillet and cook over medium heat for about 5 minutes or until tender. Set aside. In a large bowl, combine milk, black pepper, egg whites and basil. Add the rice, spinach and cooked vegetables to the egg and milk mixture, mixing well. Coat a one-quart casserole dish with nonstick cooking spray. Add the vegetable and rice mixture to the casserole dish. Cover and bake for 30-35 minutes or until completely heated through.