½ tsp salt
Bring the cider in a sauce pan to a boil, then turn down the heat and cook for around 45 minutes until about ¼ c remains. Combine the apple cider, cream, butter, granulated sugar, brown sugar, corn syrup, and salt in a large saucepan.
Bring the mixture to a boil over medium-high heat, stirring frequently.
Continue to cook, stirring constantly with a rubber spatula, until the mixture reaches 252°F on a candy thermometer, about 15-20 minutes.
Pour the caramel into a parchment-lined 8x8 inch baking pan.
Allow to cool completely, at least 2 hours.
Once cooled, sprinkle with sea salt, then lift the caramel out of the pan using the parchment paper and cut into 1-inch pieces.
