1. Heat oven to 325 degrees F. Coat two 6-indentation doughnut pans with nonstick cooking spray.
2. In a large bowl, whisk flour, baking soda and salt. In a small bowl, whisk 3/4 cup of the apple cider, the sour cream, brown sugar, eggs, butter, ginger and vanilla extract until smooth. Add milk mixture to flour mixture; whisk until smooth.
3. Spoon batter into a large resealable plastic bag. Cut off a corner and squeeze batter into prepared indents, about 2/3 full. Smooth tops. Bake at 325 degrees F for 13 to 15 minutes, until doughnuts spring back when lightly pressed. Cool in pan on rack 3 minutes.Cinnamon Sugar
4. Stir granulated sugar and cinnamon together in a small bowl. Carefully remove doughnuts from pans and brush tops lightly with additional apple cider. Quickly toss in cinnamon sugar to coat.