Wash grapes and put in a mixing bowl. Mix softened cream cheese, sour cream, sugar and vanilla. Pour over grapes and gently mix, making sure all grapes are covered with cream cheese mixture. (I mix in a little of the brown sugar at this point, but you can wait and put it all on top.) Place in container with tight fitting lid and refrigerate. When ready to serve, pour contents in serving bowl and top with brown sugar and chopped pecans. NOTE: To toast pecans, chop, place about 2 tablespoons of butter in skillet and melt. Add pecans and sprinkle with Kosher salt; toast, stirring gently. Be careful not to burn as nuts will burn easily due to their natural oils coming out while toasting.