Pour 1 ½ cups of fresh apple cider into a small saucepan over medium heat. Simmer gently for 15 to 20 minutes until the cider reduces down to exactly ½ cup plus 2 tablespoons. Remove from heat and allow to cool to lukewarm. (Set aside the 2 extra tablespoons for the glaze).

Preheat your oven to 350°F (175°C). Grease an 8.5x4.5-inch or 9x5-inch loaf pan and line with parchment paper with overhang on the sides for effortless removal.

In a medium mixing bowl, whisk together the flour, baking powder, baking soda, fine sea salt, ground cinnamon, nutmeg, and allspice until evenly distributed.

In a large bowl using a hand mixer or stand mixer, beat the softened butter, brown sugar, and granulated sugar on medium-high speed for 2 to 3 minutes until light, pale, and fluffy.

Beat in the eggs one at a time, followed by the sour cream and vanilla extract, scraping down the bowl as needed.

With the mixer on low speed, alternate adding the dry flour mixture and the cooled ½ cup of reduced cider in two additions, mixing just until combined. Do not overmix.

Spoon the thick, aromatic batter into the prepared loaf pan, smoothing the top evenly with a spatula.

Bake for 50 to 55 minutes, or until golden brown and a wooden skewer inserted into the center emerges clean with just a few moist crumbs.

Let the cake cool in the pan on a wire rack for 15 minutes, then lift it out using the parchment overhang onto the cooling rack.

While the cake is still warm to the touch, brush the top and sides generously with the melted butter. Sprinkle the cinnamon sugar mixture over the top, letting it adhere into a sparkling, crunchy bakery donut crust.

In a small bowl, whisk the powdered confectioners' sugar with the 2 tablespoons of reserved reduced apple cider until a thick, pourable glaze forms.

Drizzle the rich cider glaze generously over the warm cinnamon sugar crust, letting it drip enticingly down the sides. Allow to set for 10 minutes before slicing into thick, tender pieces.