Prepare the Cake:

1. Preheat the Oven: Preheat your oven to 350°F (175°C) and grease a 9×13-inch baking pan with cooking spray or butter.
2. Mix the Cake Batter: Prepare the red velvet cake mix according to the instructions on the box. If you’re using buttermilk for extra flavor, replace the water with buttermilk as the recipe directs.
3. Bake the Cake: Pour the cake batter into the prepared baking pan and bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean.
4. Cool the Cake: Let the cake cool in the pan for about 10-15 minutes before moving on to the next step.

Make the Pudding Filling:

5. Prepare the Pudding: While the cake cools, in a medium bowl, whisk together the vanilla pudding mix and milk. Add powdered sugar to the mixture, then whisk in heavy cream to create a smooth filling.
6. Poke the Cake: Once the cake has cooled slightly, use the handle of a wooden spoon or a fork to poke holes all over the surface of the cake. The holes should be evenly spaced and go deep into the cake.
7. Add the Filling: Pour the prepared pudding mixture evenly over the cake, ensuring that the filling seeps into all the holes. Use a spatula to gently spread it and ensure it covers the cake’s surface completely.

Top the Cake:

8. Add the Topping: Spread the whipped topping evenly over the pudding layer, smoothing it out for a beautiful finish.
9. Decorate (Optional): For a festive touch, sprinkle red and green sprinkles on top, or add fresh berries, mini chocolate chips, or holiday-themed candies for extra decoration.

Let it Chill:

10. Chill the Cake: Refrigerate the cake for at least 1 hour to allow the pudding to set and the flavors to meld together. The cake will absorb the filling, making it moist and flavorful.