cups chopped semi sweet chocolate, with several large chunks
Sea salt for finishing (optional)
In a small bowl, whisk together the flour, baking soda, cornstarch, and salt.
In another bowl, beat together the butter and sugars until smooth. Add in the egg and yolk and beat until smooth. Beat in the vanilla extract then stir in the flour until just combined. Stir in the chocolate chunks until evenly distributed.
Refrigerate the dough for at least 2 hours or overnight. If refrigerating overnight, you'll need to take the bowl out of the fridge about a half hour before you plan to bake these so they're scoopable.
Preheat the oven to 350 degrees (I highly recommend an oven thermometer!). Line two baking sheets with parchment paper. Scoop the dough out into scant ¼ cup portions. Place on the baking sheet, about 3 inches apart. Bake for 11-13 minutes or until set on the outside, but still puffed and a bit gooey in the center, rotating the pans halfway through. Remove from oven and sprinkle with sea salt, if desired. Allow the cookies to set up for about 5 minutes then remove to a cooling rack to cool completely (or eat them warm!)