In a small saucepan reduce the apple cider in half to 166g or a scant ⅔ cup. Allow it to cool at room temperature, or make it ahead and store it in the refrigerator.

In a large bowl, whisk together the all-purpose flour, baking powder, kosher salt, and 1 teaspoon cinnamon and set aside. In a separate bowl, whisk together the sour cream and apple cider reduction.

Line a baking sheet with plastic wrap and then dust the surface of the plastic wrap generously with flour.

In the bowl of a stand mixer fitted with the paddle attachment or with a hand mixer in a large bowl, beat butter and sugar until a sandy mixture forms. Slowly add the yolks and beat on high speed until pale yellow and fluffy, about 2 minutes.

With the stand mixer on low, alternately add the flour mixture and the wet ingredients (sour cream mixture) to the bowl in several additions. Stop the mixer when the dry ingredients are fully incorporated.

Transfer the dough to the flour-dusted plastic wrap, dust more flour over the top of the dough, and fold the edges of the plastic over the top to cover. I press the dough out into a flattened circle about 2 inches thick to help it chill faster. Refrigerate for 60 minutes.

Line a baking sheet pan with parchment paper, spray the paper with nonstick spray, and set aside.

Generously dust a work surface with flour. While the dough is still on the plastic wrap, dust the top of the dough with flour. Turn the dough out onto your floured surface, floured side down. Lightly dust the top with more flour.

Working quickly to keep the dough cool, roll out the dough to ½ inch thick and brush any excess flour from the top of the dough. Use a 3-inch and 1 ¼ - inch ring cutters, round cookie cutters or a glass to cut the donuts and holes. Lightly tap the cookie cutter in flour before cutting each donut. Place the donuts and donut holes on the prepared sheet pan.

Cover the sheet pan with plastic wrap, but do not let the plastic touch the top of the donuts. Chill in the refrigerator for 2 hours. At this step, I let mine chill overnight.

Before frying, set up your frying station! Place a wire rack on a rimmed baking sheet or over paper towels. Use a slotted spoon or spider to remove the donuts from the oil, and whisk together the sugar and cinnamon for the cinnamon sugar coating.

Pour oil into a fryer or a Dutch oven, making sure the oil is at least 2 inches deep. Heat the oil to 325° F. Adjust the heat to keep the temperature between 325° and 330°F while frying.

Gently place three donuts in the fryer, keeping the remaining donuts in the fridge. Once they rise to the surface, cook for 30 seconds and flip them with a slotted spoon. Fry until the bottom develops a nice golden brown color, about 80 seconds. Flip it again and then fry for another 80 seconds or until the color is a nice, even golden brown.

Transfer to a wire rack set over a sheet pan or paper towels.

Once the donut is barely cool enough to handle, dip the donut in the cinnamon sugar and place it back on the wire rack. Dipping a hot donut will ensure that the sugar sticks! If they are cool and dry, then the coating will just fall off.