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.
In a serving dish or individual cups, layer the cheesecake mixture with graham cracker crumbs, starting with a layer of the cheesecake mixture, followed by a layer of graham cracker crumbs.
Repeat the layers until all ingredients are used, finishing with a layer of graham cracker crumbs on top.
Cover and refrigerate the salad for at least 1 hour to allow the flavors to meld together.
Serve chilled.