Pour 2 cups apple cider into a medium saucepan and bring to a boil over medium-high heat. Reduce heat to medium and simmer until cider has reduced to 1/2 cup, about 15-20 minutes. It should be syrupy and coat the back of a spoon. Remove from heat and let cool completely. Reserve 3 tablespoons for the glaze.

Preheat oven to 350°F. Thoroughly butter a 12-cup bundt pan, getting into every crevice, then dust with flour and tap out excess. This prevents sticking better than baking spray.

In a large bowl with a hand mixer or in a stand mixer fitted with the paddle attachment, beat butter, granulated sugar, and brown sugar on medium-high speed until light and fluffy, about 3 minutes. Scrape down sides of bowl.

Beat in eggs one at a time, mixing well after each addition until fully incorporated. The mixture should look smooth and pale.

In a separate bowl, whisk together flour, baking powder, cinnamon, nutmeg, allspice, and salt.

With mixer on low speed, add dry ingredients in three additions alternating with the reduced cider in two additions, beginning and ending with dry ingredients. Mix just until combined and no flour streaks remain. The batter will be thick.

Spoon batter into prepared pan and smooth the top. Bake until a toothpick inserted in the center comes out clean and the cake pulls slightly away from the pan edges, 50-55 minutes. Let cool in pan on a wire rack for 15 minutes, then invert onto rack and cool completely, about 1 hour.

Whisk confectioners' sugar with reserved 3 tablespoons reduced cider until smooth and pourable. Drizzle over cooled cake, letting it drip down the sides. Let set for 15 minutes before slicing.