In a saucepan over medium heat, bring the apple cider to a boil. Reduce to simmer and let it reduce until the volume is slightly less than 1 cup.
Meanwhile, in a separate bowl, combine the sugar, flour, baking powder, baking soda, salt, and spices. Set aside.
When the apple cider is reduced, remove from heat and add the butter. Mix until the butter is fully melted, then whisk in the cream, eggs (one at a time), and vanilla.
Heat a heavy saucepan with 3" of oil until the temperature reads 365 F.
Combine the wet and dry ingredients, stirring just until it holds together. Add more flour if the mixture is too wet.
Pat out on a floured surface, cut out doughnuts, and fry a few at a time for two minutes on each side.
When each doughnut is done, let the excess oil drip off and immediately dredge in cinnamon-sugar.
Recipe by The Kitchen Paper at http://c02.ddd.mwp.accessdomain.com/apple-cider-doughnuts/