In a mixing bowl, stir together the pudding mixes and 3 cups milk. This will make instant pudding.
In the bowl of a stand mixer, whip 2 cups of heavy whipping cream for 2-4 minutes to make homemade whipped cream.
Fold the whipped cream into the pudding mixture, until just combined.
Line the bottom of the baking pan with graham crackers (or other cookie of choice).
Add half the whipped pudding mixture, spread evenly.
Add another layer of graham crackers or other cookies.
Add the second half of the whipped pudding mixture, spread evenly.
Add another layer of graham crackers or other cookies. Set aside while you make the ganache.
In a microwave-safe bowl, combine 1 cup heavy whipping cream and the chocolate chips. Microwave in 30-second intervals, stirring in between, until just combined.
Pour the chocolate ganache over the top layer of the eclair cake. Spread evenly.
Cover with plastic wrap and refrigerate for at least 8 hours and up to 24 hours. Serve cold.