• Preheat oven to 350 degrees.

Filling

• Line a springform pan with parchment paper. Place oversized paper over the base of the pan, and then clip sides of pan on. The paper will stick out around the sides. This step makes for easy removal from the pan.
• I also spray both the pan and parchment paper generously with non-stick baking spray to ensure nothing sticks.
• Warm the milk, vanilla, and half of the sugar until all sugar dissolves. Avoid boiling to prevent skin forming over your milk mixture.
• Whisk egg yolks and remaining sugar together until it's lightened in color (pale yellow). Add cornstarch and whisk to combine well.
• Slowly stream the hot milk mixture into the egg mixture while stirring constantly, until fully incorporated. Return the custard base to sauce pan and place over medium heat to thicken. Stir constantly to prevent scorching.
• Once the mixture thickens and coats the back of a spoon, cook for an additional minute or so and remove from heat.
• Add chocolate to the hot custard and stir until fully melted. At this point, I like to strain the custard through a fine mesh strainer to remove any possible lumps.
• Cover with plastic wrap, ensuring it fully touches the surface to prevent a skin from forming. Cool while preparing the crust.

Crust

• Place cookies into a food processor and pulse until evenly crushed into fine crumbs. Add melted butter and pulse to combine.
• Press into prepared pan and bake 10 minutes to set (at 350 degrees).

Bake

• Pour the cooled custard over pre-cooked base and bake in preheated oven 45 - 60 minutes at 350 degrees. I began checking around the 40 minute mark just to be sure I don't over bake. (Every oven is different and it's always best to check early). The custard is done when it is still slightly jiggly but not liquid.
• Cool on the counter to room temperature. Then, transfer to refrigerator overnight.
• Slice and serve cold or room temperature, with freshly made whipped cream.