The Crust: Blend graham crumbs, ½ cup pistachios, and melted butter in a food processor for 30–40 seconds until clumpy. Press firmly into the bottom of a 9×13 dish. Freeze for 20 minutes.
Cream Layer: In a bowl, beat the 8 oz whipped topping, cream cheese, and sugar with a hand mixer for 2–3 minutes until smooth. Spread evenly over the chilled crust and refrigerate.
Pudding Layer: Whisk the pudding mixes and milk until thick and lump-free. Spread carefully over the cream cheese layer.
Final Layer: Immediately spread the remaining 8 oz of whipped topping over the pudding.
Set: Cover and refrigerate for at least 8 hours or overnight.
Garnish: Just before serving, sprinkle the ¼ cup of chopped pistachios over the top.