CRUST: Crush shortbread cookies with a food processor until fine crumbs. Combine crumbs with melted butter and press evenly into a 9×13-inch pan. Bake at 350˚F for 8-10 minutes, until crust is set and lightly golden. Place baked crust in freezer to chill.
CREAM CHEESE: Using an electric hand mixer, beat the cream cheese and powdered sugar together in a large bowl until smooth. Set aside.
WHIPPED CREAM: Whip the heavy cream and powdered sugar together in an electric stand mixer with the whisk attachment until stiff peaks.
Add half of the whipped cream to the cream cheese mixture. Beat together with the electric hand mixer until fully combined. Set aside.
PUDDING: In a large bowl, whisk together the milk and instant pudding mix until thickened.
ASSEMBLY: Remove the crust from the freezer. Dollop, then spread the cream cheese layer evenly over the cooled crust. Next, dollop then spread the pistachio pudding evenly over the cream cheese layer. Lastly, dollop then spread the remaining whipped cream over the pudding layer.
Cover the pan with plastic wrap and refrigerate the pistachio dessert for a minimum of 2 hours to overnight. Alternately freeze for 1 to 1.5 hours (no longer) if serving the same day. Top with chopped pistachios before serving.
Notes
Keep fillings cold. When not in use, place the bowls of cream cheese, whipped cream, and pistachio pudding in the fridge to keep cold.
Store leftovers covered in the fridge for up to 3-4 days.
Cut with a hot, dry knife. Rinsing the knife in hot water and drying the knife between cuts for crisp slices.
Do NOT freeze this dessert for long term storage. The pudding and whipped cream may weep (release liquid) after thawing and the creamy texture may be compromised.
This is a great make-ahead dessert as the layers set better with more time in the fridge. Make it the day before for best results.