Line an 8-inch square pan with parchment and grease it lightly.

Combine the cream, sugar, corn syrup, salt, and butter in a heavy pot.

Cook over medium heat, stirring, until the butter melts and the sugar dissolves. Continue cooking, stirring often, until the mixture reaches 245–248°F on a candy thermometer.

Take the pot off the heat and stir in the vanilla.

Pour the caramel into the prepared pan and let it cool completely at room temperature.

Cut into squares and wrap each piece in waxed paper.