Pour 1½ cups apple cider into a small saucepan and bring it to a gentle boil over medium heat. Bring the cider to a gentle boil and let the cider simmer until there is approximately 1/2 of a cup remaining in the saucepan (this should take approximately 10-20 minutes). Remove from the heat and let cool.
Then preheat an oven to 350 degrees F and spray a donut pan with a non stick cooking spray.
In a medium bowl, whisk together 2 cups all-purpose flour, 1 teaspoon baking soda, ¾ teaspoon baking powder, 1 teaspoon ground cinnamon, ¼ teaspoon ground nutmeg, and ¼ teaspoon salt.
In a separate large bowl, whisk together 1 large egg, ½ cup brown sugar, and ½ cup granulated sugar until well combined. Whisk in 1 tablespoon melted butter. Add the cooled reduced apple cider, ½ cup room-temperature milk, and 1 teaspoon vanilla extract. Stir until combined.
Pour the mixture evenly into the donut pan filling each one about halfway full. I find that it’s easiest to use a piping bag to fill the donut pan or place the batter in a large ziplock bag and cut the corner off the bag to pipe the batter into the pan.
Then bake for 10-11 minutes until a toothpick inserted into the center of the donuts comes out clean. Let the donuts cool in the pan for 5 minutes and then transfer them to a wire rack to cool completely.
For the Topping:
In a shallow bowl, combine 1 cup granulated sugar, 1 teaspoon ground cinnamon, and ? teaspoon ground nutmeg. Place 6 tablespoons melted butter in a separate shallow bowl.
Once the donuts have cooled slightly and can be handled. Dip the donuts in the melted butter and then coat them with the cinnamon sugar topping mixture.
Serve the donuts immediately while warm and enjoy!
Notes
Leftovers can be stored at room temperature for up to 2 days or refrigerator in an air tight container for up to 5 days.