Sweet Potato Casserole

My mom used to buy sweet potato casserole from the deli for Thanksgiving (she is not much of a cook). I spent some time trying to figure out the recipe and I think I have finally got it right. It tastes just like sweet potato pie.

For casserole:
1 large can of yams
1/2 c butter
1 tsp vanilla
1/2 c packed light brown sugar
1 egg

For topping:
1/2 c packed light brown sugar
1/3 c flour
1/2 c pecans
1/3 c melted butter

1. Mash the canned yams. Add butter, vanilla, brown sugar, and egg and mix well. Pour in greased 8x8" or 9x9" glass dish.
2. Combine ingredients for topping and spoon over casserole.
3. Back for 30-35 minutes at 350 degrees.