In a medium bowl, add the cream cheese, sour cream, granulated sugar, and vanilla. Use an electric hand mixer (or stand mixer) to beat together until smooth.
Place the grapes in a large mixing bowl, add the cream cheese mixture, and gently stir to combine until all the grapes are covered.
Cover and refrigerate for 30 minutes to chill.
Just before serving, transfer to a serving bowl, and sprinkle the brown sugar and chopped pecans on top.
