1 pkg. frozen chopped spinach, cooked according to directions
1 can cream of mushroom soup
1 tbsp. grated onion
1/8 c. (1/2 stick) butter, softened
3/4 c. grated sharp cheese
1 beaten egg
1 c. stuffing mix (I use Pepperidge Farm Herb)

Mix all ingredients, place in greased 2-quart casserole. Bake 30 minutes at 350 degrees; if made ahead and cold, bake 40 minutes. Serves 6-8.