Begin by crushing the Oreo cookies into fine crumbs, leaving half a cup aside for topping later. In a mixing bowl, combine the crushed Oreos with melted butter, and stir until evenly coated. Press this mixture firmly into the bottom of a 9x13 inch dish to form a sturdy base for your Easter Dirt Cake Casserole.

In a large mixing bowl, beat together the softened cream cheese and unsalted butter until smooth and creamy, taking about 2-3 minutes. Gradually mix in powdered sugar until fully combined. Gently fold in the thawed whipped topping until the mixture is light and fluffy.

In another bowl, whisk together the instant vanilla pudding mix and cold milk until thickened, which should take about 2 minutes. Let the mixture rest for five minutes to fully set, then fold the pudding into the cream cheese mixture until completely incorporated.

Carefully spread the creamy filling over the prepared Oreo crust, ensuring it’s even and smooth. Sprinkle the reserved Oreo crumbs on top for extra crunch. Add mini Oreo cookies and pastel candies as toppings.

Cover the assembled casserole with plastic wrap and refrigerate for at least two hours, preferably overnight, to enhance flavor melding.