In a small saucepan over medium-high heat, bring 1 cup of unfiltered apple cider to a boil. Simmer vigorously for 8 to 10 minutes until reduced down to exactly 1/4 cup of thick, fragrant amber cider syrup. Let cool for 5 minutes.

Preheat your oven to 350°F (175°C). Line two large baking sheets with parchment paper.

In a medium bowl, whisk together all-purpose flour, cream of tartar, baking soda, salt, cinnamon, and nutmeg.

In a large mixing bowl (or stand mixer with paddle attachment), beat softened butter, granulated sugar, and light brown sugar on medium speed for 2 minutes until creamy and fluffy.

Beat in the egg yolk, vanilla extract, and cooled reduced apple cider syrup until completely incorporated. Gradually stir in the dry flour mixture on low speed just until combined (do not overmix).

In a small shallow bowl, whisk together the sugar, cinnamon, allspice, and ginger for the rolling mixture.

Scoop dough into 1 1/2 tablespoon balls (about 35g each). Roll smoothly between palms, then roll generously in the spiced sugar until completely encrusted.

Arrange dough balls 2 inches apart on prepared baking sheets. Bake at 350°F (175°C) for 9 to 11 minutes until the edges are lightly golden and set, and the centers remain puffy and soft with beautiful crinkly tops.

Immediately after pulling the baking sheet from the oven, firmly tap (bang) the baking sheet onto your stovetop or counter 2 to 3 times to settle the cookies into gorgeous crinkly ripples. Let rest on the baking sheet for 5 minutes before transferring to a wire rack. Serve warm!