Preheat your oven to 350°F and line a baking sheet with parchment paper.
Cook the butter in a skillet over medium heat for 3-4 minutes until browned and nutty.
Transfer the butter to a bowl and let it cool for 5 minutes.
Mix the brown sugar, eggs, and vanilla into the butter until the mixture is smooth.
Add the flour, oats, baking soda, and salt, stirring until a dough forms.
Fold in the chocolate chunks gently with a spatula.
Roll the dough into tablespoon-sized balls and place 2 inches apart on the sheet.
Flatten the tops slightly with your palm.
Bake for 8 minutes, then remove and tap the pan on the counter to flatten the cookies.
Bake for another 2-3 minutes until the edges are golden.
Cool on the sheet and sprinkle with flaky sea salt if desired.