Line an 8×8-inch square baking tin with parchment. Grease generously with butter, oil, or cooking spray.

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

Meanwhile, in a large saucepan combine sugar, corn syrup, apple cider, and 5 g salt, and cook to medium caramel color (about 365° F / 185° C on a candy thermometer).

Remove from heat and add warmed cream and butter mixture, then wait for a moment until the bubbles subside.

Return caramel pan to heat and cook mixture to approximately 250° F / 120° C, or slightly longer for a firmer caramel. (The caramels shown here were cooked to 253° F, which produces a somewhat firm caramel that will hold its shape, yet is still soft enough to chew easily!)

Immediately pour hot caramel mixture into prepared pan. Allow to set at least 8 hours, or overnight.

Remove caramel slab from pan and peel away the parchment. Sprinkle generously with coarse sea salt, and press it gently into the caramel.

Cut caramel slab into squares or rectangles with a sharp, well-oiled knife.

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