Preheat oven to 425. In stand mixer, or large mixing bowl, cream softened butter, turbinado sugar, dark brown sugar by mixing it together on medium speed. Mix for 2-3 minutes, or until well incorporated.
Divide dough into 5-6 large pieces. Form each piece into a round ball, and place, evenly spaced out, on a large cookie sheet with silicone mat or parchment paper. Sprinkle a pinch of flaky salt on each cookie.
Bake for 5-6 minutes. Cookies will be gooey, and shiny, but the dough won't look wet. Sprinkle a pinch of flaky salt on each cookie. Using a rubber spatula, push in edges to form a cookies with even thickness throughout. Let sit to cool for at least 10-15 minutes.