1. Preheat oven to 350 degrees. Grease a 9X13 pan.
2. Reserve 2/3 cups cake mix and set aside. Mix remaining cake mix, margarine and 1 egg. Put in prepared pan.
3. Bake for 15-20 minutes until golden brown.
4. Beat together 3 eggs, vanilla, reserved cake mix, corn syrup and brown sugar.
5. Pour over baked cake in pan.
6. Sprinkle pecan pieces on top.
7. Bake for 30 -35 minutes. Cool on wire rack for 20 minutes.
8. Cut into squares.
9. May be served with vanilla ice cream.