Simmer Cider Reduction: In a small saucepan over medium heat, simmer 1 ½ cups apple cider for 12 to 15 minutes until reduced to exactly ½ cup. Let cool to lukewarm.

Whisk Dry Ingredients: In a large bowl, whisk flour, baking powder, baking soda, ground cinnamon, nutmeg, ginger, allspice, and salt.

Whisk Wet Ingredients: In a separate bowl, whisk melted butter, brown sugar, granulated sugar, eggs, buttermilk, vanilla extract, and cooled reduced cider until smooth and emulsified.

Fold Batter: Pour wet ingredients into dry ingredients. Fold gently with a spatula just until combined and no dry flour streaks remain. Do not overmix.

Prep Donut Pans: Preheat oven to 350°F (175°C). Spray two standard 6-cavity donut pans generously with nonstick cooking spray.

Pipe Batter: Transfer batter to a gallon zip-top or piping bag with the corner snipped off. Pipe batter into donut cavities, filling each about ¾ full.

Bake: Bake for 10 to 12 minutes until donuts spring back lightly when touched and a toothpick inserted in the center comes out clean. Cool in pan for 5 minutes.

Coat & Serve Warm: In a shallow bowl, mix granulated sugar, ground cinnamon, and pinch of salt. Melt ½ cup butter in another bowl. Dip each warm donut generously in melted butter on all sides, then dredge immediately in the cinnamon sugar mixture until completely coated. Serve warm!