Wash and dry grapes thoroughly and place them in large bowl.
In another bowl, combine softened cream cheese, sour cream, sugar and vanilla. Gently stir the cream cheese mixture into the grapes until all of the grapes are well-coated. Spread into a 9" X 13" baking pan.
Next, mix the crumbled butterfingers, chopped pecans and brown sugar in a small bowl. Sprinkle this topping over the grapes. Chill for 2 - 4 hours before serving.