In a large mixing bowl, combine the softened cream cheese, Greek yogurt, powdered sugar, and vanilla extract. Use a hand mixer or whisk to blend until smooth and creamy.
In a separate bowl, gently mix together the strawberries, blueberries, pineapple chunks, and mini marshmallows.
Fold the cream cheese mixture into the fruit mixture until everything is well coated.
If using, stir in the chopped pecans or walnuts for added crunch.
Cover the bowl with plastic wrap and refrigerate for at least 1 hour to allow the flavors to meld.
Serve chilled, and enjoy your refreshing cheesecake fruit salad!