Mom's Sweet Potato Casserole

2 lg. cans sweet potatoes 1 c. pecans chopped
1 stick margarine, melted 1 tsp. vanilla
1/2 c. white sugar 21/2 c. marshmallows
1/2 c. brown sugar

Cream sweet potatoes, margarine, sugar and vanilla. Pour mixture into casserole dish. Top with pecans. Bake at 350 for 30 minutes. Top with Marshmallows during the last 10 minutes of cooking.