Preheat oven to 350°F. Spray a donut pan with nonstick spray. Set aside.
In a small saucepan, over high heat, bring the apple cider to a rapid boil and cook about 12 minutes, or until the apple cider is reduced by half. Cool completely.
In a large bowl, whisk flour, brown sugar, baking powder, salt, baking soda, and spices. In a small bowl, whisk eggs, melted butter and cooled cider; stir into dry ingredients just until moistened.
Pour in the buttermilk and stir.
Spoon the batter by teaspoon into a donut baking pan and fill each donut tin until it is 2/3rd full.
Bake at 350 degrees for 10 minutes. Bake in batches until all batches are baked.
In a small bowl, combine 2 cups powdered sugar and 1 cup apple cider.
Drizzle the apple cider glaze over the donuts and serve.