Line bottom of an ungreased 9- x 13-inch baking dish with one-third of the graham crackers.
In a large bowl, whisk together pudding mix and milk; add whipped topping, stirring until mixture thickens.
Spread half of pudding mixture over graham crackers in baking dish. Repeat layers with one-third of graham crackers and remaining pudding mixture. Top with remaining graham crackers. Spread with chocolate frosting. Cover to chill. for 2 hours
One box of graham crackers contains 3 individually wrapped packages of crackers. Use one package for each layer of this decadent no-bake dessert.