Start by melting the unsalted butter in a medium saucepan over medium heat. Stir occasionally until the butter starts to foam, then keep an eye on it as it begins to turn golden brown. This should take about 5-7 minutes. Once it reaches a deep amber color and gives off a nutty aroma, remove it from the heat and let it cool slightly.
In a large mixing bowl, combine the browned butter and 1 ½ cups of granulated sugar. Use a whisk to blend them until smooth. Add the eggs, one at a time, mixing well after each addition. The mixture should be creamy and slightly fluffy.
In another bowl, whisk together the all-purpose flour, baking soda, cream of tartar, and fine sea salt. Gradually add this dry mixture to the wet ingredients, stirring until just combined. Be careful not to overmix; a few lumps are perfectly fine.
Cover the dough with plastic wrap and refrigerate it for at least 30 minutes. Chilling the dough helps the cookies maintain their shape and enhances the flavors.
While the dough is chilling, preheat your oven to 350°F (175°C) and line your baking sheets with parchment paper.
In a small bowl, mix together the remaining ½ cup of granulated sugar and the 2 teaspoons of ground cinnamon. This will be used to roll your cookie dough balls in, creating that signature snickerdoodle texture.
Once the dough has chilled, scoop out tablespoon-sized portions and roll them into balls. Roll each ball in the cinnamon sugar mixture until fully coated.
Place the coated cookie balls on the prepared baking sheets, spacing them about 2 inches apart. Bake in the preheated oven for 10-12 minutes, or until the edges are lightly golden. The centers may look slightly underbaked, but they will continue to set as they cool.
Allow the cookies to cool on the baking sheet for about 5 minutes before transferring them to a cooling rack. Enjoy these Brown Butter Snickerdoodles warm or at room temperature—either way, they’re a delightful treat!
