Combine the crushed wafers and margarine and mix well.
Press into the bottom of a 9 inch springform pan.
Bake at 325 degrees for 10 minutes.
Melt the chocolate chips in the top of a double boiler over boiling water.
Beat the egg yolks in a small bowl.
Combine the cream cheese, 1/2 cup of the sugar and vanilla in a mixing bowl and beat until smooth and fluffy.
Stir in the melted chocolate and the beaten egg yolks.
Beat the egg whites in a small mixing bowl until soft peaks form.
Add the remaining 1/2 cup sugar gradually, beating until stiff peaks form.
Fold the egg white mixture into the chocolate mixture.
Fold in the whipped cream and pecans.
Pour evenly over the cooled chocolate wafer crust and freeze.
Defrost in the refrigerator 45 minutes before serving.
Decorate with whipped cream and serve.