Fry butter and onions until golden. Cook 9 slices of lasagna noodles until tender. Butter pan (9 x 13 inch) slightly. Prepare potatoes as for six (directed on package). While hot add cheese and mix until melted. Layer 3 noodles on pan, spread half of potatoes, then add 3 more noodles and remainder of potatoes, ending with 3 more noodles, Pour melted butter and onions over top. Cover and bake 45 minutes at 300 degrees. Serves 6.