In a large bowl, whisk together the pudding mixes and milk until thickened.
Fold in the Cool Whip until evenly combined with the pudding mixture.
In a 9x13-inch baking dish, arrange a single layer of graham crackers. Top with half of the pudding mixture.
Add another layer of graham crackers and the remaining pudding mixture, spreading evenly.
Top with a final layer of graham crackers.
Microwave the chocolate frosting for about 15-20 seconds to soften, then spread evenly over the top layer of graham crackers.
Cover and refrigerate for at least 4 hours, or overnight, for the graham crackers to soften.