Preheat oven to 350 degrees. Use parchment paper or a silpat mat to line a baking sheet.
Heat up the butter in a small saucepan over medium heat. Once the butter starts to boil, you'll want to stir frequently as the butter goes through a couple stages. The butter will get foamy. Be patient. You are not done yet and you need to keep stirring. You are looking for the butter to turn a deep amber color. From start to finish, it only takes about 5-6 minutes to brown butter. When the butter starts to turn that deep amber color and smells buttery and nutty, it's done. Remove from heat. Let the butter cool for 20 minutes.
Add the brown sugar, granulated sugar, egg, vanilla, baking soda and salt to a large mixing bowl. Pour the cooled butter into the same bowl and hand mix with a spatula or a large spoon.
Add the flour into the bowl and continue to stir until the dough is complete mixed. Mix in the chocolate chunks.
Scoop out about 2 TBSPs of dough for smaller cookies (or 1/4 cup dough for even BIGGER cookies). and place dough balls on prepared pan (12 cookies to a pan if small cookies and 6 to a pan if BIG cookies).
Bake for about 10-11 minutes. Remove from oven. Sprinkle with sea salt. Let cool on tray for 10 minutes. Transfer cookies to cooling rack. NOTE: Baking time will be longer if you make BIG cookies.