Preheat oven to 350 Spray a 2 or 2 ½ quart casserole with non stick spray. Pour one can of the drained peas into the bottom of the casserole dish. Thinly slice half the butter , placing slices evenly on top of the peas. Sprinkle half of the dehydrated onions over peas/butter. Empty one can of the cream of mushroom soup onto the peas/butter/onions and gently smooth to the edges. Sprinkle 1 cup of the cheese evenly over soup. Sprinkle ½ cup of the crushed chips evenly over cheese. Repeat the layers again as above, starting with the peas and ending with the chips. Bake in the oven until bubbly.