Cracker: 2 cups， butter: 1/2 cup， sugar: 2 tablespoons， cream cheese: 8 oz， sugar: 4/3 cups， cornstarch: 2 tablespoons， vanilla: 1 tablespoon， egg: 3， sour cream: 1 cup
1In small bowl toss together crackers, butter, and 2 tablespoons sugar. Reserve half mixture for garnish. Press the other half onto the bottom and 2^1/4 inches up sides of 9 inches pan. Chill in freezer while preparing filling
2In large mixing bowl beat cream cheese on medium speed of electric mixer until fluffy. Add 4/3 cups sugar, cornstarch and vanilla. Beat until combined after each addition. Stir in sour cream.
3Pour into crust. Bake at 325•F about 1 hour or until center is almost set. Cool on wire rack for 15 minutes. Loosen sides of pan. Continue cooling on wire rack for 45 minutes more.
4Sprinkle top with reserved crumbs. Refrigerate at least 3 hours. Garnish as desired.