Bring apple cider to a boil in a heavy bottomed pot. Reduce heat to medium/medium-low to maintain a steady bubble, and cook until cider is reduced to 1/2 cup, about 30-60 minutes. Stir occasionally and watch it closely toward the end so it doesn’t burn.
Strain reduced cider and return to a clean pot. Stir in light brown and granulated sugar, salt, cinnamon, and heavy cream.
Bring to a boil and cook over medium-low heat, stirring occasionally, until the caramel reaches 230 degrees F on a candy thermometer for caramel sauce, or 245-250 degrees F for dipping apples.
Caramel will thicken as it cools. Store, covered, in the refrigerator for up to one week. I like to store my caramel in a microwave safe container, so that I can easily warm it back to a pourable temperature by heating in 10 to 15-second intervals.
Caramel cooked to the temperature for sauce will thicken in the refrigerator, but still remain pliable.Caramel cooked to the temperature for apple dipping will solidify. If making ahead for apples, be sure to store the caramel in a microwave safe container. Warm in 15-second intervals at half power, until the caramel is fluid again.