Preheat the oven to 350 degrees, and prepare the yellow cake mix according to the package instructions. Bake in a well greased 9×13 baking dish for the length of time listed on the box.
Let the cake cool.
Mix together the pudding mix and milk in a mixing bowl and whisk well to combine. Let sit for 5 minutes to thicken.
Using the handle of a large cooking spoon, poke holes all over the surface of the cake.
Pour the pudding over the cake, making sure it gets down into the holes. Chill the cake in the fridge for several hours.
Place the chocolate frosting into the microwave for 15 second intervals until softened and able to be poured.
Pour the frosting over the cake, and spread it out into a smooth layer. Serve immediately or chill again before serving if desired.