Recipe from King Arthur Flour
2 cups (454g) heavy cream
1 cup (312g) light corn syrup
2 cups (397g) granulated sugar
6 tablespoons (85g) butter, salted or unsalted
1/2 cup (170g) boiled cider *see note below
1/2 teaspoon salt
1/2 teaspoon cinnamon
1/4 teaspoon ginger
1/4 teaspoon freshly ground nutmeg
*I made my own boiled cider by simmering a 48oz bottle of apple cider on the stove until reduced to 1/7th the volume. (Mark starting volume with a wooden skewer or chopstick to keep track of progress). It took me about 2 hours.
Line an 8″ x 8″ baking pan with parchment paper, leaving an overhang on all sides. The wider the parchment paper is, the better.
Combine the cream, corn syrup, sugar, butter, and boiled cider in a 4-quart, heavy-bottom, deep saucepan. (pictured below is 8-quart pan. If in doubt, err on the side of a larger pan) Bring the mixture to a boil over high heat, stirring to dissolve the sugar. Reduce to medium-high heat and cook, without stirring, until the mixture reaches 248°F on a candy thermometer, 20 to 30 minutes, depending on your particular stove.
Remove the pan from the heat; stir in the salt and spice.
Pour the hot mixture into the prepared pan. Let it stand for 12 to 18 hours at room temperature before cutting into 1″ squares.
See full recipe and instructions here