Scrub potatoes and thinly slice. Cook, covered, in enough boiling water to cover for 4 to 5 minutes or till nearly tender. Drain. Run cold water over potatoes in colander. Drain and set aside.
In a large saucepan heat oil. Add onions, celery, garlic, and black pepper; cook for 5 minutes or till vegetables are tender. Mash half cup of the garbanzo beans; add to vegetable mixture along with the remaining garbanzo beans, red beans, peas, sweet pepper, soup, milk, cumin, and coriander. Gently stir to combine.
In a greased 2 litre casserole (with cover), place a single layer of potato slices. Spoon bean mixture on top and cover with remaining potato slices in layers, overlapping if necessary.
Bake shepherd's pie, covered, in a 350 degree overn for 35 minutes. Uncover and top with cheese. Bake 10 minutes more or until cheese melts.
Makes 5 servings.