• Preheat the oven to 350°F. Grease a 9 x 13-inch baking dish or pan with cooking spray and set aside.

Make the Cake Batter

• In a large mixing bowl, combine the yellow cake mix, oil, eggs and 1 cup of the milk.
• Use an electric mixer to mix the batter until everything is combined.

Bake the Cake

• Pour the batter into the greased baking dish and bake for 25 to 30 minutes or until a thin knife inserted in the middle comes out clean.
• Let the cake cool to room temperature.

Make the Pudding

• Pour the remaining 2 cups of milk into a large mixing bowl and whisk in the banana pudding mix until it starts to thicken.
• Let the pudding rest for 2 to 3 minutes.

Add the Pudding to the Cake

• Use the handle end of a wooden spoon to poke holes about 1 inch apart and 2 inches deep all over the surface of the cake.
• Spread the banana pudding over the top of the cake evenly, pressing it into the holes as you go. Alternatively, you can pipe about half of the pudding into the holes and spread the rest of the mixture over the top of the cake.

Add the Toppings

• Slice 2 of the bananas into ¼-inch wide medallions and place them in a single layer of the pudding.
• Spoon the whipped topping on top of the cake and smooth it out.

Chill the Poke Cake

• Cover the cake with plastic wrap and chill for at least 4 hours.
• Top with extra banana slices and crushed vanilla wafers, if liked, just before serving.
• Serve chilled.