Brown the Butter

Cut butter into pieces and place in a light-colored saucepan

Melt over medium heat, stirring occasionally

Continue cooking as butter foams

Watch for golden brown bits at the bottom and a nutty aroma

Immediately pour into a heat-safe bowl

Cool for 20–30 minutes until warm, not hot

Make the Dough

Mix cooled brown butter and sugar until smooth and glossy

Beat in egg and egg yolk

Add vanilla extract

In a separate bowl, whisk flour, baking soda, and salt

Gradually mix dry ingredients into wet just until combined

Chill the Dough

Cover dough tightly

Refrigerate for at least 1 hour

Shape the Cookies

Preheat oven to 350°F (175°C)

Line baking sheets with parchment paper

Scoop dough into 1½–2 tablespoon portions

Roll into balls and coat in sugar if desired

Place 2½ inches apart on baking sheet

Bake

Bake for 10–12 minutes

Edges should be set, centers soft

Cool on baking sheet for 5 minutes

Transfer to a wire rack to cool completely