Line an 8×8-inch square baking tin with parchment in a criss-cross fashion, allowing a 1-inch overhang on all sides. Spray with nonstick spray.

In a small saucepan, simmer 240 milliliters (1 cup) apple cider over medium heat until reduced to 120 milliliters (1/2 cup), about 20 minutes.

In a small saucepan, warm cream, butter, ground cinnamon, and ground nutmeg.

Meanwhile, in a large, heavy-bottomed stock pot, stir together granulated sugar, corn syrup, apple cider reduction, and fine sea salt. Cook over medium-low heat until syrup turns golden brown and resembles honey, about 15 minutes, or until it reaches 290° F (143° C) on a candy thermometer.

Remove from heat. Slowly pour in the warm cream, then wait until the bubbles subside.

Return to medium-low heat and cook to approximately 255° F-260° F (124°-126° C) on a candy thermometer.**

Immediately pour into prepared tin.

Sprinkle generously with coarse or flaky sea salt.

Loosely cover pan with a sheet of greased aluminum foil. Allow to sit at room temperature until firm, at least 8 hours, or overnight.

Lifting by the parchment, remove caramel slab from pan. Transfer to a large cutting board, then peel away the parchment.

With a sharp, well-oiled chef’s knife, slice into squares or rectangles.

Wrap caramels in parchment squares. Store in an airtight container at room temperature for up to 2 weeks.