Line a large baking sheet with parchment paper and set aside.

Combine sugar, corn syrup and water in 3-quart heavy saucepan. Cook over medium heat, stirring occasionally, 8-12 minutes or until sugar is dissolved and mixture comes to a full boil.

Add butter; continue cooking, stirring occasionally, 15-25 minutes or until candy thermometer reaches 280°F or small amount of mixture dropped into ice water forms hard but pliable strand.

Stir in peanuts; continue cooking, stirring constantly, 10-12 minutes or until candy thermometer reaches 305°F or small amount of mixture dropped into ice water forms hard brittle strand.

Remove from heat and stir in baking soda.

Pour mixture immediately onto prepared baking sheet; spread evenly to about 1/4-inch thickness. Cool completely.

Break into pieces. Store in an airtight container.