1-Make the Crust: Preheat your oven to 350°F and spray a deep-dish pie pan with cooking spray. Pulse the 20 regular-stuffed chocolate sandwich cookies in a food processor until finely ground, then add the 3 tablespoons of melted unsalted butter and pulse until moistened. Press the mixture evenly into the bottom and up the sides of the pie pan, then bake for 10 minutes or until fragrant and set. Let it cool on a wire rack before moving on.

2-Make the Filling: In a small saucepan, whisk together the 1 1/3 cups granulated sugar and 4 large eggs. Cook over medium-low heat, whisking constantly, until the mixture reaches 160°F and coats the back of a metal spoon. Remove from heat, stir in the 8 ounces melted bittersweet baking chocolate and 2 teaspoons vanilla extract until smooth, then cool to room temperature (around 75°F), stirring occasionally. Next, beat the 10 tablespoons unsalted butter with an electric mixer until light and fluffy, about 2-3 minutes. Gradually add the cooled chocolate mixture and beat at high speed for 5 minutes until fluffy. In a separate bowl, beat the 1 1/3 cups cold heavy cream until it thickens, add the 4 teaspoons powdered sugar, and beat until stiff peaks form. Gently fold the whipped cream into the chocolate mixture. Pour the filling into the cooled crust and smooth it evenly, then chill the pie for at least 6 hours.

3-Make the Topping: Beat the 1 cup cold heavy cream, 2 tablespoons powdered sugar, and 1 teaspoon vanilla extract with an electric mixer on high speed until stiff peaks form. Top the chilled pie with this whipped cream and garnish with chocolate shavings or cocoa powder if desired. For dietary adaptations, consider using vegan substitutes in steps involving eggs and butter, and opt for gluten-free crusts. Here is a quick table summarizing the preparation times to help you plan: