In a medium saucepan over medium heat, melt the butter. Stir constantly. Watch it closely; the magic happens in seconds. After a few minutes, the butter will darken and emit a nutty aroma. It’s the browning that transforms the flavor.

Once it’s achieved that rich brown color, remove it from the heat and let it cool slightly.

In a large bowl, combine the brown sugar and granulated sugar. Add the warm, browned butter and whisk until the mixture is smooth and creamy.

The warmth from the butter will dissolve the sugars slightly, creating a lovely base.

Add the egg, whole milk, and vanilla extract to the sugar-butter mix. Whisk until everything is blended. This step ensures incorporation of all flavors.

In a separate bowl, whisk together the flour, baking soda, and sea salt. This ensures that the leavening agent and salt are evenly distributed for optimal baking.

Gradually fold the dry ingredients into the wet mixture. Mix just until you see the dough starting to come together. Over-mixing can lead to tougher cookies.

Gently fold in the chopped chocolate and walnuts. A mix of chunks and chips means you'll get pockets of gooey chocolate in every bite.

Cover the dough with plastic wrap and pop it in the refrigerator for at least two hours (or overnight, if you can wait!).

Chilling helps enhance the flavors and improves the cookie’s final texture.

Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper. Scoop portions of dough onto the sheet, spacing them about two inches apart.

Bake for 10-12 minutes. They should be golden brown on the edges with a soft center.

Allow the cookies to cool on the baking sheet for a few minutes before transferring them to a wire rack. This step helps them firm up a bit. That’s it! Time to dig in!