4 lg. baking potatoes (about 2 lbs.)
4 med. size sweet potatoes (about 2 1/2 lbs.)
3 tbsp. butter
1 sm. onion, minced
3 tbsp. all-purpose flour
2 tsp. salt
1/4 tsp. coarsely ground black pepper
2 1/2 c. milk
2 (10 oz.) pkgs. frozen chopped spinach, thawed & squeezed dry

In 8-quart saucepan over high heat, heat unpeeled baking potatoes and sweet potatoes and enough water to cover to boiling. Reduce heat to low; cover and simmer 20 to 30 minutes until potatoes are just fork tender but not soft. (Sweet potatoes may cook faster.) Drain and cool potatoes until easy to handle.

Meanwhile preheat oven to 375 degrees. In 2-quart saucepan over medium heat, in hot butter, cook onion until tender, about 5 minutes. Stir in flour, salt and pepper until blended. With wire whisk, gradually stir in milk and cook, stirring constantly, until sauce boils and thickens. Peel baking and sweet potatoes, cut into 1/4 inch thick slices.

In greased 2-quart casserole, arrange half of the potato slices; top with all the spinach; pour half of the sauce on top. Repeat with remaining potatoes and sauce. Cover casserole and bake 30 minutes. Uncover and bake 30 minutes longer or until casserole is hot and bubbly and top is browned. Makes 8 accompaniment servings.