In a large mixing bowl, beat the softened cream cheese, powdered sugar, and vanilla extract until smooth and creamy.
Gently fold in the whipped topping until well combined.
In a separate bowl, combine the sliced strawberries, blueberries, and mini marshmallows.
Add the fruit mixture to the cream cheese mixture and gently fold until evenly mixed.
Refrigerate the salad for at least 1 hour to allow the flavors to meld.
Before serving, layer the cheesecake salad in a serving dish or individual cups, and sprinkle the graham cracker crumbs on top for added crunch.