Reduce the Apple Cider: In a medium saucepan over medium heat, bring the 2 cups of fresh apple cider to a brisk simmer. Simmer uncovered for 20-25 minutes until reduced to exactly 1/2 cup of rich, concentrated amber syrup. Reserve 2 tablespoons for the glaze and set the remainder aside to cool to room temperature.

Prep Pan & Dry Ingredients: Preheat your oven to 350°F (175°C). Generously grease a 10-to-12-cup fluted bundt pan with softened butter and dust thoroughly with flour or cinnamon sugar, tapping out any excess. In a large bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, nutmeg, and allspice.

Cream Butter & Sugars: In a stand mixer fitted with the paddle attachment (or using a handheld electric mixer), beat the softened butter, granulated sugar, and brown sugar on medium-high speed for 3-4 minutes until pale, fluffy, and lightened in texture.

Incorporate Wet Ingredients: Beat in the eggs one at a time, mixing well after each addition and scraping down the sides of the bowl. Beat in the vanilla extract. Whisk together the cooled apple cider reduction and buttermilk in a measuring cup.

Combine & Bake: With the mixer on low speed, alternate adding the flour mixture in three batches and the cider-buttermilk mixture in two batches, starting and ending with the flour. Mix just until combined—do not overmix. Pour the thick batter evenly into the prepared bundt pan and smooth the top with a spatula.

Bake to Golden Perfection: Bake at 350°F for 48 to 55 minutes, or until a wooden skewer inserted into the center comes out clean or with a few moist crumbs. Cool in the pan on a wire rack for 15 minutes, then invert onto the wire rack to cool completely.

Glaze & Serve: In a medium bowl, whisk together the confectioners sugar, reserved cider reduction (or cream), melted butter, and cinnamon until a silky, pourable ribbon forms. Slowly drizzle the glaze over the cooled bundt cake, letting it cascade down the fluted ridges. Let the glaze set for 10 minutes before slicing and enjoying!