In a small saucepan over medium heat, bring the apple cider to a simmer. Simmer and reduce it to 1/2 cup. This will take about 20 minutes. Check on it often, it will reduce quickly towards the end. Set aside to cool for at least 15 minutes.
1 1/2 cups Apple cider
Preheat oven to 350ºF. Spray the donut pans with non-stick baking spray that contains flour.
In a medium bowl, whisk the all-purpose flour, baking powder, baking soda, cinnamon, nutmeg, allspice, cloves, and kosher salt until combined.
2 cups All-purpose flour, 3/4 tsp Baking powder, 1 tsp Baking soda, 1 1/2 tsp Ground cinnamon, 1/4 tsp Ground nutmeg, 1/4 tsp Ground allspice, 1/8 tsp Ground cloves, 1/2 tsp Kosher salt
In a large bowl, whisk the butter, egg, granulated sugar, dark brown sugar, buttermilk, and vanilla extract together until well combined. Add the dry ingredients and reduced apple cider, whisk just until combined.
2 tbsp Unsalted butter, 1 large Egg, 1/2 cup Buttermilk, 1/2 cup Granulated sugar, 1/2 cup Dark brown sugar, 1 1/2 tsp Vanilla extract
Spoon the batter into the donut pan, filling only halfway. Bake for 10-12 minutes, until a toothpick inserted in the center comes out clean. Cool in the pan for 5 minutes, then transfer to a wire rack over a baking sheet.
Melt the butter in a small bowl. In a shallow bowl, whisk together the granulated sugar, cinnamon, nutmeg, and allspice. Brush the entire donut with melted butter, then coat the donut in the cinnamon sugar mixture. Repeat with the remaining donuts.
6 tbsp Unsalted butter, 1 cup Granulated sugar, 1 1/2 tsp Ground cinnamon, 1/4 tsp Ground nutmeg, 1/8 tsp Ground allspice