Start by preparing the yellow butter cake mix according to the package's directions. Pour the batter into a lightly greased 9x13 baking dish. Bake according to the temperature and time guidelines on the cake box.
Once baked, take out the cake and let it cool. When cooled, use a wooden spoon's handle to poke holes throughout the cake, spacing them roughly an inch and a half apart.
In a medium-sized bowl, whisk together the instant vanilla pudding, milk, and vanilla extract.
Remember to set aside ½ cup of the pudding mixture. Then, promptly pour the remaining pudding over the cake.
Chill the cake in the refrigerator for an hour.
For the ganache, mix the butter, both types of chocolate chips, heavy cream, and vanilla in a medium bowl. Microwave in 30-second increments, stirring after each, until the chocolate is fully melted and combined.
Gently spread the ganache over the cake. For best results, refrigerate for at least 4 hours, or even overnight.
