Preheat your oven to 350°F (175°C) and grease a donut pan generously.
In a small saucepan, heat the apple cider over medium until it boils, then simmer for 10-15 minutes until reduced to about 1/2 cup. Allow to cool slightly.
In a large mixing bowl, combine melted butter, egg, brown sugar, granulated sugar, vanilla extract, and cooled reduced apple cider. Whisk until smooth.
In a separate bowl, sift together all-purpose flour, baking powder, baking soda, ground cinnamon, ground nutmeg, ground ginger, and salt.
Gradually mix the dry ingredients into the wet mixture, stirring gently until just combined.
Transfer the batter into a piping bag or zip-top bag and pipe into the donut pan, filling each cavity halfway.
Bake for 12-15 minutes until a toothpick inserted comes out clean.
While the donuts bake, mix granulated sugar and cinnamon in a shallow bowl for coating.
Allow the baked donuts to cool in the pan for about 5 minutes, then transfer to a wire rack to cool completely.
While warm, dip each donut into the cinnamon-sugar mixture for even coverage.
Notes
Serve on a decorative platter and consider drizzling with icing for an extra touch.