Brown the Butter

• Place the butter in a medium saucepan over medium heat.
• Melt the butter, stirring frequently, until it begins to foam and golden-brown specks form at the bottom.
• Continue cooking until the butter smells nutty and develops a rich golden color.
• Immediately pour it into a heatproof bowl, including the browned bits.
• Let the butter cool for 15–20 minutes until soft but no longer hot.

Prepare the Cookie Dough

• In a large mixing bowl, combine the cooled brown butter, granulated sugar, and brown sugar.
• Beat until smooth and creamy.
• Add the egg, egg yolk, and vanilla extract. Mix until fully incorporated.
• In a separate bowl, whisk together the flour, baking soda, baking powder, and salt.
• Gradually add the dry ingredients to the butter mixture, mixing just until a soft dough forms.
• If the dough feels too dry or crumbly, add 1 tablespoon of milk.

Chill the Dough

• Cover the bowl and refrigerate the dough for 30–45 minutes.
• Chilling helps the cookies hold their shape and allows the brown butter flavor to develop.

Shape the Cookies

• Preheat the oven to 350°F (175°C). Line baking sheets with parchment paper.
• In a small bowl, combine the granulated sugar and cinnamon, if using.
• Scoop the dough into balls, about 1½ tablespoons each.
• Roll each ball in the sugar mixture and arrange on the prepared baking sheets, leaving about 2 inches between cookies.

Bake the Cookies

• Bake for 10–12 minutes, until the edges are lightly golden and the centers look slightly soft.
• Remove from the oven and allow the cookies to rest on the baking sheet for 5 minutes.
• If desired, gently press the edges into a round shape using a round cookie cutter while the cookies are still warm.

Cool and Serve

• Transfer the cookies to a wire rack and let them cool completely.
• Serve with coffee, tea, or a glass of milk.
• Enjoy their crisp edges, soft centers, and rich nutty brown butter flavor.