How to Make It
Line 2 baking sheets with parchment paper. In a mixing bowl, combine flour, salt, baking powder, and baking soda; set aside.
In the bowl of a stand mixer fitted with the paddle attachment, cream together butter and sugars on medium-high until well combined, about 3 minutes. Scrape down sides of bowl, add corn syrup and beat for an additional minute. Add vanilla and egg; beat on medium high for 3 minutes.
Add dry ingredients and mix on the lowest setting until flour is just combined. Add chocolate chips and chopped chocolate. Stir a few times until chocolate is evenly distributed.
Roll 2-tablespoon portions of dough into balls and place 2 inches apart on prepared baking sheets. Refrigerate 1 hour.
Preheat oven to 350°F. Bake cookies, rotating halfway through, until edges are lightly browned and the center is still soft, about 12 minutes. Transfer to wire rack to finish cooling.
Chilling the cookie dough for an hour helps the cookie to bake evenly and maintain a soft, chewy texture.