Turn on your oven to 375°F (190°C).
In a medium saucepan, melt the butter over medium-low heat. Continue cooking, swirling occasionally, until the butter foams and the bits at the bottom turn a golden brown. Remove from heat and let cool until no longer hot to touch, 10 to 15 minutes.
1 cup (227 grams) unsalted butter
Sift or whisk together the flour, cream of tartar, baking soda, cinnamon, and salt in a small bowl.
2 ¾ cups (350 grams) all-purpose flour, 2 teaspoons cream of tartar, 1 teaspoon baking soda, ½ teaspoon cinnamon, ½ teaspoon salt
Using a stand mixer or hand mixer, beat the cooled brown butter with the brown sugar and granulated sugar until well combined.
1 cup (196 grams) brown sugar, ½ cup (100 grams) granulated sugar
Add the eggs one at a time and the bourbon, beating one minute after each addition. Scrape down the bowl as necessary.
2 large eggs, 2 tablespoons bourbon
Mix the dry ingredients in on low speed until just combined.
Use a #40 cookie scoop or two spoons to scoop cookie balls containing about 1½ tablespoons of dough. Before baking, drop the cookie balls one by one in a small bowl with the additional sugar and cinnamon, and gently roll the snickerdoodle dough until it is fully covered.
¼ cup (50 grams) granulated sugar, 1 tablespoon cinnamon
Place on a silicone or parchment-lined baking sheet, spacing at least two inches apart. You'll need three baking sheets for the whole batch, or wait a one cookie sheet is completely cool before adding a second set.
Bake 8 to 10 minutes, until the edges of your snickerdoodles are set but the centers are soft.
Cool on the baking sheet for 10 minutes before transferring to a rack to cool completely.