Boil apple cider over high heat until reduced to a thick syrup, about 1/2 to 1/3 cup. Usually takes 35-40 minutes. Stir occasionally.
Line an 8 inch square baking pan with parchment paper (cross crossed) and set aside. Mix together your cinnamon and salt in a separate bowl and set aside.
Once the cider is reduced, remove from heat and stir in the butter, sugars, and heavy cream.
Once stirred, return the pot to the stove on medium high heat and continue cooking. Using a candy thermometer, cook until mixture reaches 252* F (about 5 minutes).
Remove from heat and stir in the cinnamon and salt mixture. Stir several times to distribute evenly.
Pour into parchment lined pan, and place in the refrigerator for 2 hours to let set.
Remove block from pan and set on cutting board. Using a well oiled knife, cut into 1x1 inch squares and wrap in parchment paper, twisting the ends.