Preheat your oven to 350°F (175°C).
Prepare the pie crust by mixing crushed cookies with melted butter and press it into a pie dish.
Bake the crust for 10 minutes and let it cool.
In a saucepan, whisk together sugar, cornstarch, and salt.
Gradually add milk and cook over medium heat until thickened.
Remove from heat and stir in chocolate and vanilla until melted.
Pour the chocolate filling into the cooled crust.
Refrigerate for at least 4 hours until set.
Whip cream with sugar until stiff peaks form.
Spread whipped cream over the pie before serving.