Boil sweet potatoes in a large pot of boiling water. When tender, remove and peel off skin. Mash 3 cups of potatoes and place in a large bowl. Add vanilla, milk, sugar, eggs, and margarine and mix thoroughly. Place in a greased casserole dish.
Mix the topping ingredients together in a small bowl. Sprinkle on top of the sweet potato casserole. Bake at 325* for 30 minutes.
note--you can use canned yams if you do not have access to fresh potatoes. 2 cans equal 3 cups of sweet potatoes.