In a medium bowl, whisk together the flour, cream of tartar, baking soda, salt, cinnamon, cardamom, ginger, cloves, and black pepper until the spices are evenly distributed.
2 3/4 cups all-purpose flour, 2 teaspoons cream of tartar, 1 teaspoon baking soda, 1/2 teaspoon fine sea salt, 1 1/2 teaspoons ground cinnamon, 1 teaspoon ground cardamom, 1/2 teaspoon ground ginger, 1/4 teaspoon ground cloves, 1/8–1/4 teaspoon finely ground black pepper
In a large mixing bowl, beat the softened butter and granulated sugar on medium speed for 2–3 minutes, until light, pale, and fluffy.
1 cup unsalted butter, 1 1/2 cups granulated sugar
Beat in the eggs one at a time, mixing well after each addition and scraping down the bowl as needed. Mix in the vanilla extract until smooth.
2 large eggs, 2 teaspoons pure vanilla extract
Add the dry ingredient mixture in two additions, mixing on low speed just until combined. Stop mixing as soon as no dry flour remains; the dough should be soft but not runny.
Cover the bowl and chill the dough for 20–30 minutes. This helps the flour hydrate and gives thicker, puffier cookies, though you can skip this step if you’re short on time.
While the dough chills, preheat the oven to 375°F (190°C). Line two baking sheets with parchment paper or silicone baking mats.
In a small bowl, stir together the granulated sugar, brown sugar, cinnamon, cardamom, ginger, and a pinch of cloves until well combined and fragrant.
1/4 cup granulated sugar, 2 tablespoons light brown sugar, 1 teaspoon ground cinnamon, 1/2 teaspoon ground cardamom, 1/4 teaspoon ground ginger, pinch ground cloves
Using a medium cookie scoop (about 1 1/2 tablespoons of dough) or your hands, form dough into balls about 1 1/4 inches in diameter. Roll each ball generously in the chai sugar coating, then place on the prepared baking sheets about 2 inches apart.
Bake one sheet at a time for 8–10 minutes, until the edges are set but the centers are still soft and slightly puffy. For extra-soft cookies, remove them closer to 8 minutes.
Let the cookies cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely. Serve warm or at room temperature.