Baked Sweet Potato Casserole

1 40-oz. can sweet potato
3/4 cup white sugar
1/2 cup melted margarine
2 eggs, beaten
1/2 tsp cinnamon
1 tsp vanilla

******** Topping ********
1 cup brown sugar
1/3 cup flour
1/3 cup melted margarine
1 cup chopped nuts

Preheat over to 350 degrees. Drain and mash sweet potato. Add all ingredients except topping. Mix thoroughly. Spread in 9 by 13 baking dish. Crumble together topping ingredients. Sprinkle over sweet potato. Bake for 25 to 35 minutes.