In a large frying pan, sauté onion, celery, and red bell pepper in butter for three minutes; add minced garlic and sauté for another minute.
In a large mixing bowl, stir sautéed vegetables, crab, pasta, sour cream, Old Bay, basil, and black pepper together; pour mixture into a casserole dish, top with mozzarella cheese, and bake at 350 degrees for 20 minutes.