kosher salt (coarse)
Line 9-inch pan with parchment paper; spray with cooking spray.
In 1-quart saucepan, heat butter, whipping cream, whiskey, vanilla and kosher salt to boiling, stirring frequently. Remove from heat; set aside.
In 3-quart saucepan, mix sugar, corn syrup and water. Heat to boiling over medium high heat. DO NOT STIR. Boil until sugar turns a light amber color and candy thermometer reads 310 F.
When sugar mixture reaches, 310F, add cream mixture. Beating with whisk, cook until thermometer reads 248F. Pour caramel into pan; cool 10 minutes. Sprinkle with seat salt; cool completely.
Cut into squares; wrap individually in parchment paper.