Preheat the oven to 350°F (175°C). Line a baking sheet with parchment paper and set aside.
In a small saucepan over medium heat, add 1/2 cup butter. Cook, stirring occasionally, for 5–8 minutes until the butter foams, turns golden-brown, and smells nutty.
Remove the saucepan from the heat and let the browned butter cool for about 5 minutes, until it is warm but not hot.
Add 1/2 cup granulated white sugar and 3/4 cup light brown sugar to the warm browned butter. Stir until the sugars are evenly moistened and the mixture resembles wet sand.
Add 1 egg and 1 teaspoon vanilla extract to the sugar–butter mixture and mix until smooth and combined.
In a separate bowl, whisk together 1 1/4 cups all-purpose flour and 1/2 teaspoon baking soda.
Fold the dry ingredients into the wet ingredients just until combined. Do not overmix.
Fold in 8 oz. chocolate chunks until evenly distributed.
Use a 2-tablespoon scoop or spoon to portion dough onto the prepared baking sheet, spacing the mounds about 2 inches apart.
Bake for 12–14 minutes, until the edges are set and lightly golden.
Remove the baking sheet from the oven and let the cookies sit on the sheet for 2 minutes.
Transfer cookies to a cooling rack and let cool completely.