Start by pouring your 2 cups of apple cider into a saucepan. Bring it to a simmer over medium heat and let it cook down to about 1 cup. This takes around 10–15 minutes. Set it aside to cool—you’ll use it in both the batter and the glaze.
While the cider cools, preheat your oven to 350°F (175°C). Grease a 10-cup Bundt pan or a 9×13 baking dish with butter or nonstick spray, then dust with flour to prevent sticking.
In a medium bowl, whisk together the flour, cinnamon, nutmeg, ginger, baking powder, baking soda, and salt. This helps distribute the spices evenly and prevents clumping.
In a large bowl, beat the butter, oil, granulated sugar, and brown sugar together until light and fluffy. This adds air to the batter and helps with texture.
Mix in the eggs one at a time, then add the vanilla. Slowly pour in ¾ cup of your reduced cider and the buttermilk. Mix until just combined.
Gradually add the dry ingredients to the wet, stirring until the batter is smooth. Pour into your prepared pan and bake for 35–45 minutes, or until a toothpick inserted in the center comes out clean. Cool in the pan for 10 minutes before turning out onto a rack.
Once the cake is mostly cooled, whisk together the powdered sugar, cinnamon, and 2–3 tablespoons of the remaining reduced cider. Drizzle or brush over the cake for a beautiful finish.