Begin by washing the grapes thoroughly under cold water. Pat them dry with a clean kitchen towel. Slice the grapes in half if desired or leave them whole for a more rustic presentation.
In a large mixing bowl, combine the softened cream cheese, sour cream, sugar, and vanilla extract. Using an electric mixer or a whisk, beat the ingredients together until the mixture is smooth and creamy.
Add the prepared grapes to the creamy dressing. Gently fold the grapes into the mixture until they are well coated.
Sprinkle the chopped pecans into the grape mixture and fold them in.
Transfer the salad to a serving bowl and sprinkle the brown sugar on top. Cover with plastic wrap and refrigerate for at least 1 hour before serving.
