In 3-quart saucepan, stir together sugar, water and corn syrup. Cook, stirring constantly, until mixture comes to a boil.
Continue cooking until mixture reaches 323°F on candy thermometer, or until it spins in 2-inch thread when spoon is raised.
Stir in peanuts, continue boiling, stirring occasionally, until mixture reaches 300°F. or until small amount of mixture when dropped into very cold water, separates into threads which are hard and brittle.
Remove from heat; stir in baking soda, butter and vanilla.
Quickly pour into two 15½ x 10½ x -inch jelly roll pans. As mixture begins to harden, pull until very thin.