- cooking spray (such as Pam®)
- 2 cups white sugar
- 1 1/2 cups heavy whipping cream, divided
- 3/4 cup corn syrup
- 1/3 cup butter
- 1 teaspoon white vinegar
- 1/4 teaspoon salt
- 1 cup chopped walnuts (optional)
- 2 teaspoons vanilla extract
- Spray a large loaf pan or 8-inch square baking dish with cooking spray.
- Stir white sugar, 3/4 cup cream, corn syrup, butter, vinegar, and salt together in a heavy pot; bring to a boil. Stir in remaining cream. Cook, stirring constantly, until caramel is 244 degrees F (117 degrees C), or until a small amount of caramel dropped into cold water forms a firm but pliable ball, 10 to 20 minutes. Remove from heat and cool briefly.
- Stir walnuts and vanilla extract into caramel; pour caramel into prepared baking dish. Cool completely, at least 1 hour. Turn baking dish over onto a flat work surface to remove cooled caramel from dish; cut caramel into serving pieces.