- 1 (18.25 ounce) box yellow cake mix (such as Duncan Hines®)
- 1 cup water
- ½ cup vegetable oil
- 3 eggs
- 2 cups cold milk
- 2 (3.5 ounce) packages instant banana pudding mix
- 1 (8 ounce) container frozen whipped topping (such as Cool Whip®), thawed
- 1 cup vanilla wafer crumbs (such as Nilla®), or to taste
- Step 1Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 9×13-inch baking dish.
- Step 2Whisk cake mix, water, vegetable oil, and eggs together in a bowl until smooth; pour into the prepared baking dish.
- Step 3Bake in the preheated oven until a toothpick inserted in the center of the cake comes out clean, 23 to 28 minutes.
- Step 4Whisk cold milk and pudding mix together in a bowl until pudding is soft and thickened, about 2 minutes.
- Step 5Poke holes into the cake using the handle of a clean wooden spoon. Pour pudding over cake, spreading evenly. Spread whipped topping over pudding layer and sprinkle vanilla wafers over whipped topping.