In a large saucepan, combine sugar, corn syrup and water; bring to a boil, stirring constantly, until sugar is dissolved. Cook, without stirring, over medium heat until a candy thermometer reads 300 degrees F (hard-crack stage).

Remove from the heat; stir in butter, vanilla extract and baking soda. Add cashews. Pour into a greased 15 x 10-inch baking pan. Cool; break into pieces.