In a large mixing bowl, beat the softened cream cheese with an electric mixer until smooth.
Gradually add the powdered sugar and vanilla extract, mixing until well combined.
Gently fold in the whipped topping until the mixture is light and fluffy.
In a separate bowl, combine the sliced strawberries, blueberries, and mini marshmallows.
Carefully fold the fruit mixture into the cream cheese mixture until evenly distributed.
Transfer the salad to a serving bowl and sprinkle the crushed graham crackers on top for garnish.
Chill in the refrigerator for at least 1 hour before serving to allow the flavors to meld.