In a large mixing bowl, combine the instant pudding mix and 4 cups of heavy cream.

Whisk or beat with an electric mixer until the mixture begins to thicken.

Gently fold in the Cool Whip and set aside.

Line the bottom of a 9x13-inch dish with a layer of graham crackers.

Spread half of the pudding mixture evenly over the crackers, then add another layer of graham crackers.

Top with the remaining pudding mixture and finish with a final layer of graham crackers.

In a microwave-safe bowl, combine the remaining 1 cup of heavy cream and the chocolate chips.

Microwave in 30-second intervals, stirring between each interval, until the chocolate is completely melted and the mixture is smooth.

Carefully pour the chocolate ganache over the top layer of graham crackers, spreading it into an even layer.

Refrigerate uncovered for at least 1 hour, or until the ganache is set.

For best results, chill for several hours before serving.

Slice and serve when ready.