Place the butter in a small saucepan over medium heat. Cook until it becomes bubbly, fragrant, and starts to smell nutty—swirl and stir the butter occasionally to prevent burning.

Watch closely for small brown bits to begin forming at the bottom of the pan—this usually happens around the 5-minute mark.

As soon as you see brown bits forming, immediately remove the pan from heat.

Pour the browned butter into your mixing bowl and let it cool for a few minutes before continuing with the recipe.

In a large mixing bowl, combine the warm browned butter with the unsweetened dark chocolate. Whisk until the mixture is completely smooth.

Add both the brown sugar and granulated sugar to the bowl. Mix until the mixture becomes light and fluffy.

Add in the eggs and vanilla extract. Whisk again until the batter is pale and airy.

Next, fold in the dry ingredients (flour, cocoa powder, baking soda) and stir until all of the dry ingredients are fully incorporated.

Fold the chocolate chunks into the dough, making sure they're evenly distributed.

Scrape down the sides of the bowl, then cover the dough with plastic wrap. Refrigerate for 1 hour.

After the first chill, use a cookie scoop to portion out the dough and place the dough balls onto a parchment-lined quarter sheet pan.

Return the tray to the refrigerator and chill the dough balls for an additional hour.

Preheat the oven to 350°F (175°C).

Bake the cookies for 9–10 minutes. The edges should look set, and the centers will appear slightly shiny on top.

Remove the cookies from the oven and immediately press 5–6 chocolate chunks into the top of each one.

Allow the cookies to rest on the baking sheet for 5–6 minutes before transferring them to a wire rack to cool completely.

Store cookies in an airtight container at room temperature for up to 3 days.