Stir in 1 1/2 cups of the all-purpose flour, the fresh rosemary and the kosher salt. Start kneading and add the unsalted butter a few chunks at a time, along with additional flour, until the butter has been incorporated and the dough is starting to pull away from the sides. Continue to add flour by the tablespoon until the dough is smooth and no longer sticks to the side of the bowl, about 8 minutes.