Okay, these are seriously good. Since I don't often work with a candy thermometer, it tends to make me nervous, but this was really easy.
Note: Mine came out slightly harder than I would have liked. I'll be playing with the temps a little soon. Might have just been my candy thermometer.
adapted slightly from Nosh with Me
3/4 cup heavy cream
1/2 teaspoon vanilla extract
rounded 1/2 teaspoon + 1/4 teaspoon flaky sea salt (I had some French grey sea salt in my pantry)
1/2 cup light corn syrup
1 cup sugar
4 tablespoons butter, cubed, at room temperature
Line a 9-inch (23 cm) loaf pan with foil and spray the inside with cooking spray.
Heat cream, two tablespoons butter, vanilla, and 1/2 teaspoon sea salt in a small saucepan until the mixture begins to boil. Remove from heat, cover, and keep warm while you cook the syrup.
In a medium, heavy duty saucepan (4 quarts, 4l), fitted with a candy thermometer, heat the corn syrup with the sugar and cook, stirring gently, to make sure the sugar melts smoothly. Once the mixture is melted together and the sugar is evenly moistened, only stir as necessary to keep it from getting any hot spots.
Cook until the syrup reaches 310ºF (155ºC). To get an accurate reading while the syrup is cooking, tilt the saucepan to make sure the bulb of the thermometer is fully submerged in the syrup.
Turn off the heat and stir in the warm cream mixture until smooth.
Turn the heat back on and cook the mixture to 260F (127C).
Remove the pan from the heat, lift out the thermometer, and stir in the cubes of butter until they’re melted and the mixture is smooth.
Pour the mixture into the prepared loaf pan and wait ten minutes, then sprinkle 1/4 teaspoon of the sea salt over the top. Set on a cooling rack and let cool completely. Once cool, lift out the foil with the caramel, peel away the foil, and slice the bar of caramel with a long, sharp knife into squares or rectangles.
Storage: These caramels can be individually-wrapped in cellophane or waxed paper. Once cut, they may stick together if not wrapped. Store in an air-tight container, and they’ll keep for about one month.