Grease a 9" pie plate with butter or shortening, set aside.

Crumble the Oreos a bit, then blitz in your food processor - filling and all - until finely ground.

Pour crumbs into a large bowl, stir in melted butter

Dump the mixture into your pie plate. Distribute crust mixture evenly over the pan, press firmly to form a pie crust with even thickness throughout.

In a medium saucepan, whisk together the sugar, cornstarch, and salt.

In a separate bowl, beat the egg yolks. Add milk - a bit at a time - whisking until well combined. Add this mixture to the pot, whisking to fully combine.

Once everything is fully combined - and being careful to scrape the bottom of the pan - bring to a just to a boil over medium-high heat, whisking constantly.

As the mixture starts to boil, turn heat down to low and continue to simmer until quite thick. Remove from heat.

Immediately add the chocolate, butter, and vanilla. Whisk constantly until the chocolate and butter are completely melted and everything is well incorporated.

Pour into the cooled pie crust, using an offset spatula or the back of a spoon to smooth and flatten the top of the filling.

Cover with plastic wrap - right against the surface of the filling - and chill for 8 hours.

Sprinkle gelatin over the cold water in a small bowl and let it absorb for five minutes.

Combine heavy whipping cream, powdered sugar, and flavor extract in a mixing bowl. Whip until soft peaks start to form.

Transfer gelatin mixture to the microwave. Heat in 10 second increments until the gelatin dissolves into the water.

Fold gelatin mixture to cream mixture, then whip until stiff peaks form.

Spread ½ of the whipped cream evenly over the chocolate pie filling, smoothing with a hot offset spatula if desired.

Pipe a lattice of chocolate sauce over the top of the whipped cream, if you’d like.

Spoon remaining whipped cream into a pastry bag set with a large star tip.

Pipe rosettes of whipped cream around the edge of the pie, as shown.

Crush some of the mini eggs, sprinkle over the rosettes. Top with whole mini eggs.

Chill until serving.