1 cup good apple cider
1 cup granulated sugar
1/4 cup unsalted butter
2 large eggs
1/2 cup buttermilk
3 1/2 cups all-purpose flour
2 teaspoons baking powder
1 teaspoon baking soda
1 teaspoon ground cinnamon
1/2 teaspoon salt
shortening for frying
Boil apple cider until it's reduced to 1/4 cup; cool.
While cider is reducing, combine flour, baking powder, baking soda, cinnamon, and salt in a large bowl; stir to combine.
Beat butter and sugar in separate large bowl until smooth. Add eggs, one at a time, until well mixed. Add buttermilk and cider, stir to combine.
Add dry ingredients to wet and SLOWLY mix at first to avoid being attacked by a flour bomb, increasing speed slightly until all ingredients are incorporated.
Line a baking sheet with parchment, sprinkle with flour, and pat dough with your hand to 1/2 inch thickness. Chill in freezer for 15 minutes. Meanwhile, line a second baking sheet with parchment and sprinkle with flour.
Run a doughnut cutter or a 3 inch circle cutter under cold water, then cut doughuts/circles from chilled dough. If using circle cutters, run a 1 inch cutter under cold water, and cut holes out of the middle of the large circles. Use the 1 inch cutter to make additional holes with smaller areas of remaining dough. Transfer half the doughnuts and holes to second baking sheet. Place baking sheets in fridge for 10 minutes.
Line several large plates with paper towels. Set aside.
Melt shortening in heavy-duty deep pot (I like my cast iron Dutch oven for this) until a temperature of 375F is reached. Fry doughnuts a few at a time until deep brown, carefully flipping over with a heat-proof tongs or <a href="http://www.amazon.com/6-diameter-Bamboo-Skimmer-Strainer/dp/B00012F3U4">spider</a> halfway through (about a minute or two total per doughnut - it goes fast, so don't take your eye off them).
Remove to paper towel-lined plates to drain. While still warm, roll in sugar or cinnamon sugar* mixture, if desired.
*To make cinnamon sugar, combine 1/2 cup granulated sugar with 1/2 teaspoon ground cinnamon; stir to combine.