Source: Take A Megabite (Recipe adapted mostly from The Novice Chef)
8 tablespoons (1 stick) butter
1 cup + 2 T unbleached flour
1/4 teaspoon baking soda
1/8 teaspoon baking powder
1/2 teaspoon kosher salt
1 cup packed brown sugar
2 teaspoons vanilla extract
For rolling -
2 heaping T brown sugar
2 heaping T granulated sugar
Heat butter in a small saucepan over medium heat until melted. Continue to cook, swirling the pan, until the butter turns golden brown. There will be small flakes of brown in the bottom of the pan. Transfer to a large bowl and set aside to cool for 20 minutes.
Preheat your oven to 350F and line two baking sheets with parchment paper. In a small bowl stir together the 2 tablespoons of brown sugar and granulated sugar. Set aside.
In a medium bowl whisk together the flour, baking soda, baking powder and salt. Set aside. Add brown sugar to the bowl with the cooled brown butter and whisk until smooth. Add the egg and vanilla and whisk until there are no lumps. Add flour mixture and stir with a wooden spoon until no flour streaks remain.
If you’d like to make 16 cookies roll the dough into a ball about 1 1/2 tablespoons in size. To make ones the size I made, divide that regular-sized cookie ball in half. Roll into a ball and roll through the sugar mixture. Place on the prepared baking sheets.
Bake for 7-12 minutes depending on the size of cookie you make. They’re done when the edges are just golden. Allow to cool on a the baking sheet for a few minutes before transferring to a wire rack to cool completely.