In a medium bowl, whisk the flour, cream of tartar, cinnamon, baking soda, and salt.
Once your brown butter is cool, add it to the bowl of a stand mixer using the paddle attachment (or use an electric hand mixer). Pour in granulated sugar and brown sugar, and beat on medium speed for about 2 minutes, stopping once to scrape down the sides of the bowl with a rubber spatula.
Add eggs and vanilla extract, and beat on medium speed for another minute, until well-combined. Use rubber spatula to scrape down the sides and bottom of the bowl again.
With mixer on low, slowly pour in the dry ingredients, and mix just until combined. Don't overmix. Cover bowl with plastic wrap and chill in the refrigerator for at least 30 minutes and up to 24 hours.
When you are ready to bake, preheat the oven to 375 degrees F and line two baking sheets with parchment paper or silicone baking mats.
Using a cookie scoop or large spoon (I used 1 tablespoon of dough for each cookie), roll cookie dough into balls, then roll them into the cinnamon-sugar mixture. You should fit 12 cookies on each baking sheet.
Bake cookies for 10 minutes. They will look quite puffy when you take them out of the oven, but give the baking sheets a few taps on the counter to help them deflate and create the perfect wrinkled texture. Let the cookies cool for 10 minutes, then transfer to a wire rack to cool completely. Repeat with remaining dough. Store cookies in an airtight container at room temperature for up to 5 days.