Cook lasagne noodles according to package directions Mash the potatoes
Add cheese to the potatoes and beat with mixer
Saute onion in margarine until soft Add 13 of the onion and margarine to the potato mixture and salt to taste Generously butter a 13 x 9 x 2-inch baking dish
Place a layer of lasagne noodles in dish then a layer of potato mixture Repeat ending with noodles
Pour butter and onion over all
Cover with foil and bake at 350 until heated through