Sweet potato pie casserole

This is so good.  I could eat the whole thing myself.
Use a 9" pie dish or an 8"x8" glass casserole.


Mix the following well, and put in the pie dish.
1  29 oz can sweet potatoes, drained of liquid and mashed well
1/2 cup sugar
1/4 cup melted margarine or butter (I use less)
1 tsp. cinnamon
1 egg
Topping: 
1 sleeve Ritz crackers, crushed
1/2 cup brown sugar
1 stick melted margarine or butter (I use 3/4)
1/2 cup chopped walnuts
Mix the topping ingredients well - I use my hands.
Spread over top of pie - try not to taste because if you're like me, there won't be enough left for the pie.
Bake for 30 minutes at 325-350.
Can also be made beforehand, kept in fridge for a day or two, and reheats well.  Bake a little longer if put in oven cold.