Reduce the apple cider. Bring the apple cider to a simmer in a pot over medium heat. Cook for 1 hour, until the mixture has reduced by 4, leaving ¾ cup. Let cool slightly, until cool enough to handle.
Preheat the oven to 350℉. Spray the donut pan generously with cooking spray.
In a large bowl whisk the apple cider reduction, yogurt, and butter.
Add the sugar and vanilla and whisk again.
Add the flour, baking powder, baking soda, salt, cinnamon, and nutmeg. Whisk well until no clumps remain and batter starts to thicken - it is good to whisk thoroughly here, we want the gluten to develop.
Fill each hole in a donut pan about halfway full with batter - I use 2 scoops of a small cookie scoop to help me get an even amount in each hole. This recipe makes about 18 donuts, so you'll need to do a second round if you only have one pan - the leftover batter will hold up resting at room temp while the first batch bakes.
Bake the donuts for 13 minutes, until the edges are just golden brown. Remove from the oven and place the tray on a wire rack for about 2 minutes to cool.
Use the thin edge of a spatula to gently remove each donut from the mold. Place the finished donuts on a wire rack and allow to cool until they are easy to handle.
Meanwhile, in a small bowl whisk together the sugar and cinnamon for the coating. Arrange the melted butter and cinnamon sugar mixture next to each other for easy coating.
Dip each donut very quickly in the butter and then toss in the sugar mixture. Do not let the donuts sit in the butter or they will soak up too much of the liquid and become soggy. Repeat with the remaining donuts. Enjoy!