Pulse the chocolate sandwich cookies in a food processor until they resemble coarse crumbs. Melt the unsalted butter and combine it with the cookie crumbs in a medium bowl, mixing well until the mixture is moistened. Press this crumb mixture firmly into the bottom of a 9x13 inch dish to create an even crust.

In a mixing bowl, beat the softened cream cheese and powdered sugar together using a hand mixer until the mixture is smooth and creamy. Gently fold in the whipped topping until fully incorporated. Spread the cream cheese mixture evenly over the prepared crust.

Spoon the strawberry pie filling over the cream cheese layer, using the back of the spoon to create an even layer. Add the blueberry pie filling on top, allowing some colors to blend slightly.

Spoon the remaining whipped topping onto the blueberry layer in asymmetrical swirls. Sprinkle star-shaped decorations over the top. Cover the dish with plastic wrap and refrigerate for at least four hours, or until set.