Wash grapes and remove stems. Set aside to air dry.
Set cream cheese out to come to room temperature.
Place sour cream and sugar in a mixing bowl, but do not mix. Set mixing bowl aside.
Cut cream cheese blocks into golf ball size pieces and place into a food processor until completely blended and the consistency is smooth. Pour the cream cheese into the mixing bowl with sour cream and sugar. Mix with an electronic mixer for two minutes on medium speed.
Gently fold the vanilla into the mixture with a spatula. Continue to fold until the vanilla is blended completely. Be careful not to over mix. The mixture should be light and fluffy.
Place all grapes into a large bowl and add dressing mixture evenly. Gently mix by hand until all grapes are completely covered. (NOTE: Grapes must be completely dry before adding dressing.) Chill until ready to serve.
Just before serving, sprinkle brown sugar and crushed pecans on top.
