Make the crustMix the Oreo crumbs with melted butter and a pinch of salt. Press the mixture into the bottom and up the sides of a 9-inch pie pan. Freeze for 10 minutes, then bake at 350°F (175°C) for 8 minutes. Let cool completely.
Prepare the mousse layerIn a mixing bowl, beat cream cheese and powdered sugar until smooth. Add vanilla and fold in the whipped topping until light and fluffy. Spread most of this mixture (reserve about ½ cup for decoration) evenly over the cooled crust.
Make the puddingWhisk the chocolate pudding mix with cold milk for 2 minutes until thickened. Pour gently over the mousse layer and spread evenly. Chill the pie for 15 minutes to help it set.
DecoratePipe the reserved mousse around the edges. Drizzle Hershey’s syrup over the top and sprinkle mini chocolate chips. Chill for at least 3 hours, preferably overnight, before slicing.
