Preheat the oven and prepare the 16.25 ounce cake mix using Ingredients to make cakeaccording to package directions for a 9x13 in baking pan. Add the 1 tablespoon vanilla extract to cake mix.
Bake according to package instructions.
Remove and while the cake is still hot, poke many holes in the top using the end of a wooden spoon so the holes are a good size. Allow to cool for 10 minutes.
In a large mixing bowl, whip together the 5.1 ounce instant vanilla pudding mix and 3 cups cold eggnog*. Fold in the 1 teaspoon pumpkin pie spice.
Spread the pudding mix over the warm cake, allowing it sink into the holes of the cake. Tap lightly on the counter to get it into all the nooks and crannies.
Cover and chill for 1-2 hours.
Frost the cake with 8 ounces whipped cream and top with crumbled 1 1/2 cups nilla wafers.
If you've tried this recipe, come back and let us know how it was in the comments or star ratings.
Video
Notes
*Most 5. ounce pudding mixes call for 3 cups of liquid, but double check and use as much eggnog as it calls for cold milk. Storage: Keep covered in the refrigerator and plan to enjoy within 3 days for the best texture. The wafers soften as the cake sits, and fresh whipped cream can lose volume.Freezing: For the best texture, refrigerate the assembled cake. Freezing and thawing can change the consistency of the pudding and whipped cream and soften the cookie topping.