Prepare the crust by finely crushing the Oreo cookies and reserving ½ cup for later. Press the remaining crumbs firmly into a 9x13 inch dish.

In a mixing bowl, beat together the softened cream cheese, unsalted butter, and powdered sugar until smooth and creamy. Fold in the whipped topping.

In another bowl, whisk the instant vanilla pudding mix with cold milk until it thickens, about 2 minutes. Let it rest for 5 minutes.

Fold the thickened pudding into the cream cheese mixture until well blended and creamy.

Spread the creamy filling over the prepared Oreo crust, then sprinkle the reserved cookie crumbs, mini Oreos, and pastel candies on top.

Cover the casserole and refrigerate for at least 2 hours to let it set.