In a 3-quart saucepan, stir together sugar, water and corn syrup. Cook, stirring
constantly, until mixture comes to a boil. Continue cooking until mixture reaches
232 degrees F on a candy thermometer, or until it spins a two-inch thread when the
spoon is raised.
Stir in peanuts. Continue boiling, stirring occasionally, until mixture reaches
300 degrees F or until a small amount of mixture separates into threads which are
hard and brittle when dropped into very cold water.
Remove from heat; stir in baking soda, butter and vanilla extract.