In a small bowl, mix together ¼ c brown sugar and ¼ c granulated sugar. Set aside.
In a medium mixing bowl, whisk together the dry ingredients ( flour, soda, baking powder and salt ). Set aside.
Place 7 tablespoon of butter in a medium saucepan and cook until it browns. Take off the heat and pour into a large mixing bowl of your stand mixer. Add the remaining butter and whisk. Add 1 ¾ c brown sugar and whisk. Let cool to room temperature.
Add egg and egg yolk and whisk. Add vanilla and whisk again.
Switch to a wooden spoon or a spatula and fold in the dry ingredients.
Refrigerate the dough for at least 30 minutes, preferably overnight. You can freeze the dough for up to 1 month.
When ready to bake, preheat your oven to 350 degrees. Line a cookie sheet with parchment paper or silpat baking mat. Scoop the cookie dough into a tablespoon size balls and roll in brown and white sugar mix. Place on baking sheet leaving 2 inches of space between the balls. Sprinkle with sea salt.
Bake 8 to 9 minutes for chewy cookies or 10 to 13 minutes for crispy cookies.
Cool on sheet for 30 seconds and transfer onto a wire rack to cool completely.