Line 2 baking sheets with aluminum foil. Coat with nonstick cooking spray.
In a large saucepan over medium heat, combine sugar and corn syrup. Heat to 250 degrees F (120 degrees C). Remove from heat, and stir in butter until melted. Gradually stir in cream. Return to heat. Cook, stirring constantly, until temperature reaches 242 degrees F (116 degrees C). Remove from heat, and stir in vanilla and pecans.
Drop by spoonful onto prepared pans. Cool completely, then wrap with plastic.