Step 1: Reduce the Apple Cider In a small saucepan over medium heat, simmer the 1.5 cups of apple cider until it has reduced to exactly 3/4 cup. This should take about 10-15 minutes. Set it aside to cool completely before using it in the batter.
Step 2: Preheat and Prepare Preheat your oven to 350°F (175°C). Generously grease and flour a 10-inch Bundt pan, or use a high-quality non-stick baking spray with flour included to ensure the cake releases easily after baking.
Step 3: Whisk Dry Ingredients In a medium bowl, whisk together the flour, baking powder, baking soda, cinnamon, nutmeg, and salt. Ensuring these are well-combined helps the cake rise evenly and distributes the spices throughout the crumb.
Step 4: Cream Butter and Sugars In a large mixing bowl or a stand mixer, beat the softened butter, granulated sugar, and brown sugar together on medium-high speed. Continue for about 3 minutes until the mixture is light, fluffy, and pale in color.
Step 5: Add Eggs and Vanilla Add the eggs one at a time, beating well after each addition. Scrape down the sides of the bowl as needed. Stir in the vanilla extract and the cooled, reduced apple cider.
Step 6: Combine Wet and Dry Reduce the mixer speed to low. Gradually add the flour mixture in three parts, alternating with the buttermilk in two parts. Begin and end with the flour. Mix only until just combined to avoid a tough cake.
Step 7: Bake the Cake Pour the batter into the prepared Bundt pan and smooth the top with a spatula. Bake for 45 to 55 minutes, or until a toothpick inserted into the center comes out clean. Let the cake cool in the pan for 10 minutes before inverting it onto a wire rack.
Step 8: Prepare and Apply Glaze While the cake is still slightly warm, whisk together the powdered sugar, apple cider, and cinnamon in a small bowl. Drizzle the glaze over the top of the cake, allowing it to drip down the sides.