Prepare 1 box yellow cake mix with ingredients needed to make cake: eggs, oil and water according to package directions for a 9×13-inch cake.

Once cake comes out of the oven, allow it to cool for just a couple of minutes.

Then, with a wooden spoon handle, begin poking holes in the cake. You want the holes to be big enough so that the pudding has plenty of room to get down in there.

In a bowl, whisk together 2 (3.4 ounce) packages instant banana pudding with 4 cups cold milk. Stir quickly until all the lumps are gone but before the mixture starts getting too thick to pour.

Pour pudding over cake, taking care to pour it right into the holes as much as possible.

Spread it all out and using the back of the spoon, gently push pudding down into the holes.

Put the cake into the refrigerator to set and cool for about 2 hours.

Once the cake has completely cooled, spread on 8 ounce tub frozen whipped topping, thawed.

Sprinkle 20 vanilla wafers, crushed onto the top of the cake before serving. Keep refrigerated.