Brown the butter. In a small saucepan, heat the butter over medium-low heat, stirring occasionally, until the butter just begins to brown and smell nutty. Keep an eye on this, as it can quickly go from browned to burnt. Once the butter is browned, removed from heat and place in a small bowl. Place in the fridge and allow butter to solidify. Once the butter is solid, remove from the fridge and let come back to room temperature.
Line a baking sheet with parchment paper and set aside. Preheat oven to 350 degrees F.
Cream the butter and brown sugar together until light and fluffy. Add the remaining ingredients except for the 1/2 teaspoon of white sugar and 1/2 teaspoon of flaked sea salt. Continue to mix the ingredients together until a dough forms. Form the dough into 1-1 1/2 inch balls and place on the prepared baking sheet. You should have about 12 cookies. Sprinkle the 1/2 teaspoon of white sugar and 1/2 teaspoon of flaked sea salt over the cookies and lightly press the sugar and salt on the tops of the cookies so that it stays put. Bake the cookies for about 20 minutes, or until the bottoms begin to turn golden brown.
Recipe adapted from Cookies & Cups