No bake pistachio dessert.
Line a 9x13 pan with Ritz crumbs and drizzle with melted butter. Make sure all the crumbs are coated and press down into the bottom of the pan to make your crust.
Whisk milk and pudding until just set and then fold in softened ice cream. Spread evenly over the top of the cracker crumbs - careful not to lift the crumbs into the pudding mixture.
Cover pan with cling wrap and let set in the fridge for 4 hours (or overnight). Top with Cool Whip and serve immediately or refrigerate.