Begin by pouring 2 cups of fresh apple cider into a medium saucepan. Bring the cider to a gentle boil over medium heat, then reduce to a simmer for about 25 minutes until it thickens down to about 1/2 cup.

While the cider cools, preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

In a large mixing bowl, whisk together 2 cups of all-purpose flour, 1 tablespoon of baking powder, 1 teaspoon of ground cinnamon, 1/4 teaspoon of freshly grated nutmeg, 1/4 teaspoon of ground allspice, and 1/4 teaspoon of salt.

In a separate bowl, beat 1/2 cup of softened unsalted butter and 3/4 cup of granulated sugar until light and fluffy, about 3-4 minutes, then add in 2 large eggs one at a time.

Gradually stir in the boiled apple cider, blending until just combined, then slowly add the dry ingredients to the wet ingredients, mixing until fully incorporated.

Divide the dough into two equal pieces and shape each into logs about 10-12 inches long, 4 inches wide on the prepared baking sheet.

Bake for approximately 25 minutes until the logs are golden brown and firm to the touch.

Let the logs cool for 10 minutes before slicing into 1-inch slices and lay them cut-side down on the baking sheet. Bake for an additional 10-15 minutes, flipping halfway through.

Transfer the biscotti slices to a wire rack to cool completely.

Whisk together 1 cup of powdered sugar and 2 tablespoons of boiled apple cider until smooth and drizzle over the cooled biscotti.