Add the 4 cups of apple cider into a medium size pot and bring to a boil on high heat.
Reduce heat to medium high and cook for about 25-30 minutes or until it reduces to 1 cup.
Reserve ½ cup of the reduced cider for glazing.
Preheat oven to 350°F (175°C) and set rack to middle position.
Grease a large bundt cake pan with pan release coat with butter or margarine.
Combine the the flour, salt, baking powder, cinnamon and all spice into a a large bowl and mix together using a whisk.
In a separate large bowl, add the ½ cup of reduced cider, granulated sugar, brown sugar, melted butter, vanilla extract and eggs extract and stir together until well combined.
Pour the apple cider mixture, and grated apples onto the flour mixture and mix together until batter consistency. You can also use hand mixer or planetary mixer with paddle attachment.
Transfer the batter to the bundt pan and even out the surface.
Place into preheated oven and bake 60-65 minutes. Insert a tooth pic or skewer into the center, it should come out clean.
Remove the cake from the oven and brush the top of the apple bunt cake with 2 tablespoons of the cider.
Cool the cake in the pan for 15 minutes, then invert onto a cooling wire rack and brush the top and sides of the cake with the cider.
Cool for 30 minutes before adding the apple cider icing.
Immediately brush the exposed surface of the cake in the pan with 1 tablespoon of the reserved cider. Let cake cool for at least 10 minutes before inverting onto wire rack.
Brush the top and sides of the cake with the rest of the apple cider and cool the cake for about 30 minutes.
Decorate the cake with the cider icing, serve and enjoy!