Brown ground beef, onions, and garlic in skillet. Drain. Add tomato sauce, olives, and mushrooms.
In a separate bowl, combine sour cream, cottage cheese, and green chilies.
In slow cooker, layer a third of the chips, and half the ground beef mixture, half the sour cream mixture, and half the shredded cheese. Repeat all layers, except reserve last third of the chips to add just before serving.
Cover. Cook on Low 4 hours.
Ten minutes before serving time, scatter reserved chips over top and continue cooking, uncovered.