1. Preheat oven to 350°F (175°C).

2. In a bowl, combine chocolate cookie crumbs and melted butter. Press the mixture into a 9-inch pie pan to form a crust.

3. Bake the crust for 8–10 minutes. Let it cool completely.

4. In a saucepan, whisk together sugar, salt, and cornstarch. Gradually add milk while whisking until smooth.

5. Place the pan over medium heat and cook, stirring constantly, until the mixture thickens and begins to bubble.

6. In a separate bowl, lightly beat egg yolks. Slowly add a small amount of the hot mixture to the yolks while whisking to temper them.

7. Return the tempered yolk mixture to the saucepan and cook for 2 more minutes, stirring constantly.

8. Remove from heat and stir in chocolate chips, butter, and vanilla extract until smooth.

9. Pour the chocolate filling into the cooled crust and refrigerate for at least 4 hours, or until set.

10. Top with whipped cream and garnish with chocolate shavings or cookie crumbs before serving.