Reduce the cider: Pour apple cider into a saucepan. Simmer over medium heat until reduced to about 1/2 cup, 15–25 minutes. Cool completely. This step deepens flavor and prevents a watery dough.

Mix dry ingredients: In a bowl, whisk flour, baking powder, baking soda, cinnamon, nutmeg, and salt. Set aside.

Cream butter and sugar: In a large bowl, beat softened butter with sugar until light and fluffy, about 2–3 minutes. Add eggs one at a time, mixing well, then blend in vanilla.

Add liquids: Stir the cooled cider reduction into the butter mixture. It may look slightly curdled—no problem.

Combine with dry mix: Add the dry ingredients in two additions, alternating with buttermilk. Mix gently just until no streaks of flour remain. The dough will be soft and slightly sticky.

Chill the dough: Scrape dough onto a lightly floured sheet of parchment, pat into a 1-inch-thick rectangle, cover, and chill 1–2 hours until firm. Chilling makes it easier to cut and helps donuts hold their shape.

Prepare the coating: In a shallow bowl, mix 1 cup sugar with 2 teaspoons cinnamon and a pinch of salt. Set near a rack lined with paper towels.

Heat the oil: In a heavy pot or Dutch oven, heat 2 inches of oil to 350–360°F (175–182°C). Use a thermometer for accuracy.

Cut the donuts: On a floured surface, roll dough to 1/2 inch thick. Use a 3-inch cutter for the donuts and a 1-inch cutter for the holes. Gather scraps, chill briefly, and re-roll once for a few extra.

Fry in batches: Carefully slide 2–4 donuts into the oil without crowding. Fry 60–90 seconds per side until deep golden brown. Maintain oil at 350–360°F; adjust heat as needed.

Drain and coat: Transfer to the rack to drain for 30–60 seconds, then toss warm donuts in cinnamon-sugar to coat thoroughly.

Fry the holes: Donut holes cook fast—about 45–60 seconds total. Drain and coat while warm.

Serve: Enjoy warm for the best texture and aroma. They’re at peak perfection within the first couple of hours.