Reduce apple cider for concentrated flavor. In a small saucepan over medium heat, simmer the apple cider, stirring occasionally, until you’re left with about 1/2 cup. Start checking at 10 minutes until you have 1/3 cup (80 ml). Mine takes between 12 and 15 minutes. Set aside to cool completely.
Preheat the oven to 350° F. Lightly grease two 6-cavity doughnut pans. Set aside.
In a medium bowl, whisk together the flour, baking powder, salt, cinnamon and nutmeg. Set aside.
In the bowl of a stand mixer (or using a hand mixer), mix together butter, brown sugar and granulated sugar on medium speed until light and fluffy, about 3 minutes. Scrape down the sides of the bowl if necessary. Add the eggs and vanilla, and mix until incorporated.
Add the flour mixture and mix just until combined (avoid over mixing). Slowly add the apple cider reduction and mix just until combined. Use a rubber spatula to scrape the sides and bottom of the bowl to remove any remaining flour pockets.
Transfer batter to a ziplock bag and cut a hole in the corner. Pipe batter into prepared donut tins, filling each cavity about three-quarters full.
Bake donuts 12 to 15 minutes or until golden brown and a toothpick inserted into one comes out clean.
Cinnamon Sugar Coating
While the donuts bake, whisk together 1/2 cup granulated sugar and 1 teaspoon cinnamon in a small bowl. In a separate small bowl, melt 6 tablespoons of butter in the microwave.
Remove donuts from oven when baked and allow them to cool for 5 minutes in the pan. Gently remove them them from the pans and while they are still warm brush with the melted butter and generously coat them in the cinnamon sugar. Serve immediately or cool to room temperature.
Notes
Apple cider donut muffins: If you don't have a donut pan, use a muffin pan! Divide batter evenly between the prepared cups and bake for 15 to 20 minutes, rotating halfway through.Mini donuts/muffins: Use a mini donut pan or mini muffin pan to make smaller portions. Reduce baking time to 8-10 minutes.Store apple cider donuts in an airtight container at room temperature for up to 3 days. Donuts are best when eaten the day they are made.