In a medium bowl, combine the crushed Oreo cookies and melted butter. Mix until well combined. Press the mixture firmly into the bottom of a 9x9-inch baking dish to form the crust. Refrigerate for 10 minutes to set.

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 well combined.

In another bowl, whip the heavy cream until stiff peaks form. Gently fold the whipped cream into the cream cheese mixture until fully incorporated.

Fold in the mini marshmallows and half of the red, white, and blue sprinkles into the cream cheese mixture.

Spread the cheesecake mixture evenly over the chilled Oreo crust. Smooth the top with a spatula and sprinkle the remaining sprinkles on top. If desired, crush additional Oreo cookies and sprinkle them over the top.

Cover the baking dish with plastic wrap and refrigerate for at least 4 hours, or until set. For best results, chill overnight.

Once set, cut into bars and serve chilled.