01 -
Melt ½ cup butter in small pan over medium heat. Cook 3-5 minutes, swirling occasionally, until butter turns amber and has nutty aroma. Transfer to bowl to cool for 5 minutes.
02 -
Preheat oven to 350°F. Line 2 baking sheets with baking mats or parchment paper.
03 -
In large bowl, beat brown butter, remaining ½ cup butter, and brown sugar with electric mixer 3 minutes until creamy. Add egg, yolk, and vanilla; mix 1 minute. Add flour, salt, and baking soda, mixing until combined. Add 1-2 tablespoons extra flour if dough seems too soft.
04 -
Refrigerate dough for at least 30 minutes.
05 -
Scoop dough onto baking sheets, spacing 2 inches apart. Bake 10 minutes until edges are golden brown and centers still soft.
06 -
Let cookies cool on baking sheet until centers are set, then transfer to wire rack to cool completely.