In a large bowl or stand mixer fitted with a paddle attachment, whip together the cream cheese, yogurt, sugars, and vanilla until smooth.
Add in the chopped apples, grapes, and walnuts and mix until evenly coated. Transfer to a large bowl and sprinkle with additional chopped walnuts and brown sugar. Enjoy immediately or place in the fridge until ready to serve.
For best flavor, place in the fridge overnight after making.