Bring egg and butter to room temperature by resting on countertops for at least an hour prior to baking.

Start making the brown butter. For best results, cut butter stick into 6-8 pads before adding to your stainless or light-colored pan without heat.

Run a paring knife under hot water to cut through the butter easily without sticking.

Place butter in a pan on medium heat and immediately turn to medium-low.

Using a wooden spoon, continuously stir the butter as it melts.

Once the butter begins to foam, stir in a circular motion and keep the butter moving in the pan.

Watch for the milk solids at the bottom of the pan as the foam subsides to begin turning brown. Once they reach a golden brown, turn off the heat and remove the pan from the stove.

Transfer brown butter to a heat-safe bowl and let rest in the refrigerator while you prepare your dry ingredients.

Preheat oven to 375º.

In a medium-sized bowl, sift together flour, salt, and baking soda.

In a large bowl, whisk together brown sugar and white sugar. Remove the brown butter from the refrigerator and pour into the sugar mixture.

Using a hand mixer, beat the sugars and butter until completely incorporated.

Add the egg and vanilla to the creamed sugar and beat again for 30-60 seconds.

Combine the dry and wet ingredients and carefully beat together until a dough forms.

Let the cookie dough rest for 10-15 minutes and let it form together if the butter is still very warm.

Add dark chocolate chunks, chopped, and reserve a few pieces to the side.

Using a one-ounce ice cream scoop, form 10-12 balls and place them on a parchment-lined cookie sheet. Add additional dark chocolate chunks to the last few balls of dough if needed.

Gently press your thumb on the top of each cookie and sprinkle a pinch of smoked sea salt flakes on top. Do not press too hard; the cookies will spread out on their own.

Bake at 375º for 9-11 minutes and immediately transfer to a cooling rack.