Preheat your oven to 350°F (175°C). Grease a 9x13-inch baking dish and prepare the yellow cake mix according to package directions. Bake for 25–30 minutes until golden and a toothpick comes out clean. Let cool for 10 minutes.

Using a wooden spoon handle or chopstick, poke holes in the cake about 1 inch apart.

In a medium bowl, whisk the pudding mixes and cold milk until smooth and thick. While the cake is still slightly warm, pour the pudding over it, ensuring the holes are filled. Press down gently with a spatula.

Cover with plastic wrap and refrigerate for at least 2 hours or overnight.

For the chocolate ganache: Heat heavy cream in a small saucepan over medium heat until simmering. Remove from heat and pour over chocolate chips. Let sit for 2 minutes, then stir until smooth. Pour the ganache over the chilled cake and spread into an even layer. Chill for another 30 minutes to set the ganache.