Preheat oven to 350°F (175°C) and prepare a 9-inch deep pie dish.

Crush 24 Oreo cookies in a food processor until fine. Mix with 3 tablespoons melted butter and press into the pie dish. Bake for 10 minutes and cool completely.

In a saucepan, whisk together granulated sugar and eggs over medium-low heat until it reaches 160°F. Stir in melted chocolate and vanilla extract, then cool to room temperature.

Beat room temperature butter until fluffy, about 3-5 minutes. Gradually mix in cooled chocolate mixture for another 5 minutes.

Whip 1 1/3 cups cold heavy cream with 4 teaspoons powdered sugar until stiff peaks form, about 3-5 minutes.

Gently fold whipped cream into the chocolate mixture until fully combined.

Pour filling into the cooled crust, smooth it out, cover with plastic wrap, and refrigerate for at least 6 hours.

Before serving, whip remaining 1 cup heavy cream with 2 tablespoons powdered sugar until stiff peaks form. Spread over pie.

Garnish with chocolate shavings or cocoa powder before slicing and serving.