Reduce the apple cider: Add the apple cider and the cinnamon stick to a medium saucepan. Bring the cider to a simmer over medium-high and reduce it until you have about ⅓ of a cup. It will be syrupy. Transfer the apple cider syrup to a medium bowl to cool. Add the apple butter, buttermilk, and the vanilla. Whisk to incorporate.
3 cups apple cider, 2 cinnamon sticks, ½ cup apple butter, ½ cup buttermilk
Combine the dry ingredients in a medium-sized bowl and set aside.
Cream together the butter, the brown sugar, and ¼ cup of granulated sugar. Beat until the mixture is light and fluffy—5 to 7 minutes. Slow the mixer and add the eggs in one at a time. Make sure each egg is fully incorporated before adding the next. Add the vanilla.
6 tablespoons unsalted butter, ¼ cup granulated sugar, ¼ cup light brown sugar, 2 large eggs, 2 teaspoon vanilla extract
Turn off the mixer and add half of the flour mixture and half of the cider mixture. Mix briefly until just incorporated. Repeat with the remaining flour and cider mixture.
Form and chill the dough: Prepare a rimmed baking sheet by lining it with parchment paper and dusting it with flour. Scrape the dough onto the prepared baking sheet. Dust your hands and the top of the dough with more flour and pat it down until it is about 3/4 of an inch thick. Cover with plastic and refrigerate for 3 hours, up to overnight.
Cut out the donuts: Punch out your donuts with a 3¼ inch round pastry cutter. Punch out the centers with a 1¼ inch round pastry cutter. Gather the scraps and repress them, try not to work the dough too much. You should end up with 18 donuts. Roll the remaining dough into holes. Cover the dough and place it back in the fridge to chill while you heat up the oil.
Heat the oil: Get your dutch oven ready and warming. Add about 3 inches of oil and set up the candy thermometer in the pan. Set the pan on low while you are preparing the donuts and then turn it up to medium-high when you are ready to start frying your donuts.
4 cups vegetable oil
Make cinnamon sugar: Combine 1 cup of granulated sugar and 1 tablespoon of cinnamon.
Get ready to make the donuts: Line a rimmed baking sheet with paper towels and set a wire rack over the top to serve as your cooling rack.
Fry the donuts: When the oil has reached 350°F, add one layer of donuts. Fry until golden brown on one side (3 min), then flip them over and fry for another 3 minutes. Fry the donut holes for 2 minutes on each side. Transfer the donuts to the wire rack and cool slightly. Toss the donuts into the cinnamon-sugar mixture while they are still warm.
1 cup sugar, 1 tablespoon ground cinnamon
RECIPE TIPS
Gluten-Free:Bob's Redmill gluten-free baking mix works great in these. Make-Ahead: Make the apple cider donut dough a day a head, cover and refrigerate until you are ready to use.