Heat the cream in the microwave or on the stovetop just until simmering. Place the chocolate in a heatproof bowl, pour the hot cream over the chocolate, and let stand for 2 to 3 minutes, then stir until smooth. Cover and let stand at room temperature for 2 hours, then whisk again.
Line the bottom of a 9 × 13-inch baking dish with one sleeve of the graham crackers.
In a large bowl, whisk the milk and pudding mix until thickened and smooth. Fold in the whipped topping.
Spread half of the pudding mixture over the graham crackers. Repeat the layers with another sleeve of graham crackers and the remaining pudding mixture. Top with the last sleeve of graham crackers, then spread with the chocolate ganache.
Refrigerate for 8 hours. Slice and serve.
Notes
You can use a 16-ounce container of chocolate frosting instead of the chocolate ganache.
