In a saucepan, bring the apple cider to a boil over medium heat. Reduce the heat and let it simmer until reduced to about 1 cup (about 15-20 minutes). Allow to cool.
Preheat your oven to 350°F (175°C). Grease and flour a Bundt pan.
In a medium bowl, sift together the flour, baking powder, baking soda, cinnamon, nutmeg, and salt. Set aside.
In a large bowl, cream the softened butter, granulated sugar, and brown sugar until light and fluffy (about 3-5 minutes).
Beat in the eggs, one at a time, followed by the vanilla extract. Mix until combined.
Gradually add the dry ingredients to the butter mixture, alternating with the cooled apple cider reduction, starting and ending with the dry ingredients.
Gently fold in the diced apples
Pour the batter into the prepared Bundt pan and smooth the top. Bake for 50-60 minutes, or until a toothpick inserted in the centre comes out clean.
Allow the cake to cool in the pan for about 15-20 minutes before inverting it onto a wire rack to cool completely.