In a medium bowl, combine the crushed Oreo cookies and melted butter until well mixed.

Press the Oreo mixture firmly into the bottom of a lined 9x9 inch baking dish to form the crust.

In a large mixing bowl, beat the softened cream cheese with an electric mixer until smooth and creamy.

Gradually add the powdered sugar and vanilla extract, mixing until fully combined.

In a separate bowl, whip the heavy cream until stiff peaks form, then gently fold it into the cream cheese mixture.

Fold in the mini marshmallows and sprinkles until evenly distributed.

Pour the cheesecake mixture over the Oreo crust and spread it evenly.

Refrigerate the cheesecake bars for at least 4 hours or until set.

Once set, cut into bars and drizzle with chocolate sauce and additional sprinkles on top before serving.