Heat chocolate and 2 tablespoons of the milk in saucepan over low heat, stirring frequently until chocolate is melted.
Beat sugar into cream cheese
Add remaining milk and chocolate mixture and beat until smooth.
Fold in whipped topping and blend until smooth.
Spoon into crust.
Freeze until firm, about 4 hours.
Garnish with additional whipped topping and chocolate curls, if desired.
Let stand at room temperature about 1 hour before serving.
Store any leftover pie in the refrigerator.