Step 1

In a medium bowl, combine pudding mix, whipped topping, and 1/4 cup chopped pistachios. Place a single layer of graham crackers in bottom of a 9- x 13-inch baking dish. Top with one-third of pudding mixture.

Step 2

Repeat layers of graham crackers and pudding 2 more times, ending with a layer of graham crackers.

Step 3

Spread frosting over top, sprinkle with remaining chopped pistachios, then cover and chill overnight, allowing graham crackers to soften. Cut into squares and serve.