Begin by removing the creamy filling from the Oreos, placing it in a small bowl for later use. Crush the cookie halves in a plastic bag until they resemble fine crumbs (about 5 minutes).

In the small bowl with the Oreo filling, microwave the cream for 2 minutes on medium power until softened. Stir until smooth and glossy.

In a large mixing bowl, pour in the cold heavy whipping cream. Whip on medium-high speed for 3–5 minutes, or until soft peaks form.

Add the melted Oreo cream and powdered sugar to the whipped cream. Mix gently on low speed for about 1 minute until combined.

Gently fold in the crushed Oreo cookies using a spatula, reserving some crumbs for topping.

Spoon the mousse into serving dishes, sprinkle with reserved Oreo crumbs, and optionally add a whole Oreo on top. Chill for up to 1 hour before serving.