01 -
Heat ½ cup of butter in a small pot over medium. Stir or swirl off and on for 3-5 minutes until it smells nutty and looks golden-brown. Pour it into a bowl and let cool about 5 minutes.
02 -
Turn oven to 350°F to preheat. Cover 2 baking trays with parchment or silicone mats.
03 -
Whip browned butter, the other ½ cup of butter, and the sugar in a big bowl using an electric mixer for 3 minutes until fluffy. Stir in egg, yolk, and vanilla, mixing for another minute. Blend in flour, salt, and baking soda until it's all together. If dough feels sticky, toss in 1-2 more tablespoons of flour.
04 -
Cover and chill mixture for at least half an hour.
05 -
Spoon dough into balls and space them 2 inches apart on baking trays. Bake for 10 minutes until edges are gold and middles stay tender.
06 -
Leave cookies on trays to finish setting, then move them to a cooling rack to cool all the way.