Preheat oven to 350 degrees. Crush 18 crackers in blender until fine. In bowl mix crackers, 2 Tbs sugar and stick of margarine. Mix until blended then press in bottom and a little up sides of spring pan. In small bowl beat eggs and 2 tsp. vanilla and let sit. In large bowl blend cream cheese, sour cream and sugar until well blended. Then add egg mixture to cream cheese mixture. Pour into spring pan over crust. Bake 350 degrees for 30 minutes. Then turn oven off but leave door closed and bake 30 minutes more with oven off. Keep in refrigerator overnite. Half hour before serving, add topping.