Make the crust: Combine the finely crushed chocolate sandwich cookies with melted butter until evenly moistened.
Press the crust: Transfer the mixture to a 9x13-inch baking dish. Press it firmly and evenly across the bottom. Refrigerate while preparing the filling.
Make the peanut butter filling: Beat softened cream cheese, peanut butter, powdered sugar, and vanilla until smooth and creamy.
Fold in whipped topping: Gently fold 1 cup of whipped topping into the peanut butter mixture until light and fluffy.
Add the peanut butter layer: Spread the mixture evenly over the chilled cookie crust.
Prepare the pudding: Whisk the instant chocolate pudding mixes with cold milk until thickened according to the package directions.
Add the chocolate layer: Carefully spread the chocolate pudding over the peanut butter layer.
Add the topping: Spread the remaining whipped topping evenly over the pudding.
Finish with candy: Scatter chopped miniature chocolate peanut butter cups over the top. Drizzle with chocolate syrup if desired.
Chill: Cover and refrigerate for at least 4 hours. For the best texture, chill overnight.
Serve: Cut into squares with a sharp knife and serve cold.