Grease a baking sheet with butter.

Mix the salt, baking soda, and tablespoon of butter in a small bowl and set aside.

In a very clean pot, heat sugar, corn syrup, and water to medium ball stage (240 degrees F) on a candy thermometer.

Add cashews and continue stirring until the temperature reaches hard crack (300 degrees F) on the candy thermometer.

Remove from heat, add in the butter, salt, and baking soda. Stir until well combine and the butter is melted.

Pour out onto the the buttered baking sheet.

Cool completely.

Break into pieces and serve.

Store in an airtight container.