Simmer Cider: In a small saucepan over medium heat, bring 1 ½ cups of fresh unfiltered apple cider to a brisk simmer. Cook for 15 to 18 minutes, swirling occasionally, until it concentrates down to exactly ½ cup. Pour into a heatproof measuring cup and cool to room temperature.

Preheat & Prep Pan: Preheat your oven to 350°F (175°C). Generously grease a 10-to-12 cup bundt pan with softened butter and dust thoroughly with flour (or use baking spray with flour), tapping out any excess.

Whisk Dry Ingredients: In a medium bowl, whisk together the all-purpose flour, baking powder, baking soda, salt, cinnamon, nutmeg, and allspice until evenly combined.

Cream Butter & Sugars: In a large mixing bowl or stand mixer fitted with the paddle attachment, beat the softened butter, granulated sugar, and brown sugar on medium-high speed for 3 to 4 minutes until light and fluffy. Add the eggs one at a time, beating well after each addition, then blend in vanilla extract.

Alternate Wet & Dry: With the mixer on low speed, add the dry ingredients in three additions, alternating with the sour cream and cooled reduced apple cider (begin and end with dry ingredients). Mix just until combined without overworking.

Bake to Perfection: Spoon the thick, fragrant batter into the prepared bundt pan and smooth the top with an offset spatula. Bake at 350°F for 50 to 55 minutes, or until a wooden skewer inserted into the deepest center comes out clean with just a few moist crumbs attached. Cool in the pan on a wire rack for exactly 10 minutes, then invert onto the wire rack to cool completely.

Cook Caramel Glaze: In a small saucepan over medium heat, melt the butter and brown sugar together, whisking until sugar dissolves. Pour in heavy cream and sea salt, bring to a gentle boil for 2 minutes, then remove from heat. Whisk in vanilla extract and sifted powdered sugar until glossy and smooth. Let cool for 5 minutes to thicken slightly.

Drizzle & Crown: Slowly ladle or pour the warm salted caramel glaze over the cooled bundt cake, letting it cascade down each sculpted ridge. Finish with a delicate pinch of flaky Maldon sea salt and slice into generous wedges!