potato lasagna

9 lasagna noodles, cooked
3 (or more ) cups shredded cheddar cheese
8 servings of instant mashed potatoes
1 large onion, chopped
2 sticks butter

Sauté onion and butter. Spray a little Pam in a 9 x 13 inch baking pan. Put a little onion and butter on bottom of pan, then 3 noodles, then 1/2 the potatoes. Sprinkle 1/3 cheese and spread on some of the butter and onion mixture, 3 more noodles and then rest of potatoes. Put 1/3 of cheese, more butter and onions then last 3 noodles. Put remaining 1/3 cheese on top. Pour on rest of onion and butter on top. Cover and bake at 350° for 25 minutes. Let stand for at least 15 minutes to set up before cutting. Can be made ahead, but cooking time will have to be adjusted as it will be coming out of the refrigerator cold instead of going into the oven already hot when just assembled.