• Preheat oven to 350°F. Spray a 9x13 baking dish or pan with cooking spray. Set it aside.
• Whisk 3 ½ cups of milk and the vanilla instant pudding together in a medium bowl for 2 minutes or until it starts to thicken. Let it rest for 4 minutes, then cover it with plastic wrap and chill while you make the cake.
  
• Combine the remaining 1 cup of milk and butter in a large microwave-safe bowl or measuring cup, and heat in the microwave in 1-minute intervals until the butter is completely melted and the milk is steaming.
  
• In a large mixing bowl, add the cake mix, eggs, and milk mixture. Use an electric mixer to mix the batter together until just combined.
  
• Pour the batter into the prepared baking dish or pan, and bake for 25 minutes or until the cake is slightly brown on top and a toothpick poked in the middle of the cake comes out clean. Rest the cake on a cooling rack at room temperature until completely cool.
  
• Once the cake is cool, pour the heavy whipping cream into a small, microwave-safe bowl, and heat in 1-minute intervals until steaming. Add the chocolate chips and corn syrup and let them stand for 3 minutes. Stir the mixture until the chocolate chips have melted and the ganache is smooth.
  

Assembly:

• Use the end of a wooden spoon or a thick skewer to poke holes in the cake about 1 inch apart. Spoon the set vanilla pudding over the cake, and spread it out evenly, ensuring that the pudding fills the holes.

  TIP: I like to put a little bit of the pudding in a plastic bag, and cut the corner, to "pipe" the pudding in to the cake holes.
  
• Pour the ganache over the cake, and smooth it out. Cover the cake with plastic wrap and chill in the fridge for at least 3 hours or until the ganache has set. Serve chilled.