Buttermilk Sweet Potato Casserole

7 med. sweet potatoes
2 sticks butter
2 eggs
1 tsp. baking powder
1 tsp. vanilla
2 tsp. cinnamon
1 c. sugar
3/4 c. buttermilk
1 1/2 c. pecans, chopped
Miniature marshmallows

Cook potatoes, peel and put in mixer bowl. Add all of the ingredients except marshmallows and mix well. Put mixture into casserole dish and bake at 350 degrees for 20 minutes. Top with miniature marshmallows. Bake 10 minutes more. Serves 12.