Put melted butter in large mixing bowl. To make 3 cups mashed sweet potatoes, peel and cut into large chunks enough sweet potatoes to equal the 3 cups - approximately 4 large. Place chunks in a large saucepan and cover with water. Cover with lid and boil potatoes until tender - approximately 15 minutes. Drain and mash potato chunks with potato masher. Measure mashed sweet potatoes to 3 cups and put in large mixing bowl with butter. Add remaining ingredients and mix all well. Pour in buttered or greased 2 quart casserole or pyrex dish.

Topping:
1 stick butter, melted
1/4 cup flour
1/2 cup sugar
1 medium egg
8-ounce can crushed pineapple, juice packed, drained

Cream butter, flour and sugar in medium mixing bowl. Add egg and pineapple. Mix well and pour on top of casserole. Bake 45 minutes at 350 degrees until golden brown on top. May add garnish for color variety.
Yield: 8 servings.