Prepare the Pudding Layer

Into a large bowl, pour both packages of instant vanilla pudding mix.

Add the 2/3 cup dry Funfetti cake mix and 4 tbsp sprinkles to the pudding mix and stir until well combined.

Add 4 cups of milk to the dry mixture. Whisk vigorously for about 2 minutes until the pudding begins to thicken and springs back slightly when stirred. Set aside.

Make the Cake Batter Whipped Cream

In a separate large bowl, pour 1 2/3 cups heavy whipping cream.

Using a hand mixer or stand mixer set on high speed, whip the cream until it starts to thicken.

Add 3/4 cup cake mix and 1 tsp vanilla to the thickening cream. Continue whipping on high until the whipped cream holds firm peaks and becomes stable. Set aside.

Build the First Oreo Layer

Pour the remaining 1/2 cup of milk into a small bowl. Life Love and Sugar

Quickly dip each birthday cake Oreo into the milk — just a quick dunk so they soften slightly without becoming mushy.

Place the milk-dipped Oreos in a single layer across the bottom of a 9×13-inch pan, arranging them side by side in a solid layer.

Add the Filling and Whipped Cream

Spread half of the prepared pudding evenly over the Oreo layer, using a spatula to smooth out the surface.

Next, spread half of the cake-batter whipped cream over the pudding, creating a smooth and even layer.

Add Second Oreo Layer

Dip the remaining Oreos quickly in the milk again and arrange them over the whipped cream in a second single layer.

Finish the Filling

Spread the remaining pudding over the Oreos, smoothing it gently.

Top with the remaining cake-batter whipped cream, spreading to cover the entire dish.

Sprinkle extra sprinkles generously over the top for a fun, festive finish.

Chill

Cover the pan and refrigerate for at least 4 hours or overnight, allowing the cookies to soften and the layers to meld into a tender, party-like cake consistency.