Preheat the oven to 350°F. Spray a deep-dish 9-inch pie plate with non-stick baker’s spray and set aside.

Add the OREO cookies to the bowl of a food processor and pulse until fine crumbs form.

Remove the cap on the lid, and with the food processor running, slowly stream the melted butter into the cookie crumbs. Mix just until the crumbs resemble wet sand.

Transfer the mixture to the prepared pie dish and press firmly into the bottom and up the sides of the pie dish to form the crust. You can use the bottom of a measuring cup or glass to help press the mixture evenly into the pie dish. This helps create a crust that holds together well once baked, chilled, and sliced.

Bake for 10 minutes. Remove from the oven and allow to cool slightly while you prepare the brownie layer.

In a small saucepan over medium-low heat, melt the butter and chocolate, stirring until smooth. Remove from the heat and allow to cool 1-2 minutes before adding to the rest of the ingredients.

In a large bowl, whisk together the light brown sugar, granulated sugar, eggs, canola oil, and vanilla extract just until well combined. The mixture will look slightly frothy at the surface.

Add 2 tablespoons of the melted chocolate to the bowl and whisk until fully incorporated. This helps temper the eggs so they do not scramble when the rest of the warm chocolate is added.

Slowly drizzle in the remaining melted chocolate, while whisking constantly, until all the melted chocolate is incorporated and the mixture is smooth.

Whisk together the all-purpose flour and cocoa powder, being sure to remove any lumps of cocoa. Add to the melted chocolate mixture and stir gently just until smooth and no dry pockets of flour remain. The batter should be thick but pourable.

Pour the brownie batter into the crust and smooth to an even layer.

Bake for 23-25 minutes or just until a toothpick inserted into the center comes out with a few moist crumbs. Do not overbake or the brownie layer will be tough once chilled.

Allow the brownie layer to cool at room temperature for 30-45 minutes or until the pie dish is cool to the touch before adding the pudding layer. Because the pudding layer needs to be refrigerated immediately after being added to the brownie layer, for safety purposes, you do not want to add a hot pie dish to the cold refrigerator or you will risk shocking the pie dish and cracking it.

In a large bowl, whisk together the egg yolks and cornstarch until well combined. The mixture will be a thick paste-like consistency. Set aside.

In a medium saucepan over medium heat, warm the whole milk, heavy cream, and granulated sugar for 2-3 minutes or just until the sugar has melted and tiny bubbles start to form around the outer edge of the saucepan. Do not bring the liquids to a boil.

Remove about ⅓ cup of the warm milk and slowly drizzle into the egg yolk mixture, while whisking constantly, until fully incorporated and the mixture is pourable.

While whisking constantly, slowly drizzle the heated egg yolk mixture into the saucepan. Cook the pudding mixture for an additional 1 to 1½ minutes, or just until thick enough to hold its shape on a spoon.

Remove the saucepan from the heat and whisk in the finely chopped chocolate, unsalted butter, and vanilla extract until well combined and smooth.

Pour the warm chocolate pudding mixture through a wire mesh strainer, over a clean bowl, to remove any lumps or cooked egg pieces. Pour the strained pudding over the brownie layer and smooth to an even layer. Immediately cover the pie, being sure to push the plastic wrap all the way onto the surface of the warm pudding to prevent a skin from forming while the pudding chills and sets.

Refrigerate the pie for 3 to 3½ hours or until the pudding layer has completely chilled and set. Do not add the whipped topping until about 30-60 minutes prior to serving.

Beat the heavy cream, powdered sugar, and white chocolate flavored instant pudding in a large mixing bowl using a handheld mixer on low speed, gradually working up to high speed, for 3-4 minutes or until stiff peaks form.

Spread the whipped topping evenly over the chilled pudding layer, being careful not to combine the layers.

Garnish with a sprinkle of cookie crumbs and semi-sweet chocolate shavings if desired before returning the pie to the refrigerator to finish chilling for an additional 30-60 minutes. This allows the whipped topping to fully firm to ensure clean slices for serving.