Gather all your ingredients to ensure a smooth baking process.

Pulse the Oreo cookies in a food processor until finely ground. Combine with melted butter and blend until well mixed.

Press the cookie mixture firmly into the base and sides of a 23cm pie dish.

Separate the yolks from the whites of the eggs. Place yolks in a medium bowl.

In a small bowl, whisk ½ cup of milk with the cornstarch until smooth.

In a saucepan, combine double cream, remaining 1½ cups of milk, salt, and sugar. Whisk until well blended and place over medium heat.

As the mixture warms, stir in the espresso powder.

Once the dairy mix reaches a simmer, carefully pour a ladleful over the egg yolks, whisking constantly. Gradually add the rest of the mixture while whisking.

Return mixture to pan and cook over medium heat, whisking constantly until thickened and smooth.

Remove from heat and stir in chopped chocolate until melted. Pour the filling into the prepared crust and top with chocolate ganache.

Refrigerate the pie for at least 4 hours, or until firm and set.

Before serving, top with whipped cream and garnish with additional Oreos if desired.