Process the cookies in a food processor until finely ground. Transfer to a bowl and add melted butter. Stir to evenly mix. Transfer to a 9-inch pie plate. Use your fingers to press the cookie crumb mixture along the bottom and sides of pie plate. Refrigerate for at least 1 hour.
Melt semisweet chocolate in a small heavy-bottomed saucepan over low heat. Stir in ¼ cup sweetened condensed milk. Immediately pour on top of cookie crust. It will start to set up once it hits the cold crust. Work quickly spreading with the back of a spoon or spatula. Once you get it mostly spread you can spray your fingers with cooking spray and even it out using your hands. It will have the consistency of fudge that is setting up.
Place back in refrigerator and make the pumpkin filling. Using an electric mixer, beat cream cheese until smooth. Gradually add in pumpkin and sweetened condensed milk. Add spices.
In a medium bowl, whisk together pudding mix and milk for 2 minutes. Add to pumpkin mixture and mix until smooth. Pour into pie pan and refrigerate at least 30 minutes.
Top with whipped topping and serve. Garnish with cookie crumbs if desired.