Preheat the oven to 350°F.
Combine the flour, salt, baking powder and baking soda in a medium mixing bowl. Set aside.
Add the room temperature butter, brown sugar and white sugar to a large mixing bowl, or the bowl of a stand mixer.
Cream the butter and sugar together on medium speed for 2 minutes, using an electric hand mixer or stand mixer.
Add the egg, egg yolks and vanilla extract to the butter/sugar mixture.
Beat on medium speed until combined.
Add the flour mixture and beat until all of the ingredients are combined.
Add the dark chocolate chunks and use a spatula to stir them into the cookie dough.
Use an ice cream scoop to scoop the cookie dough out onto a baking stone or parchment lined baking sheet.
Place in the oven and bake for 12-14 minutes.
Remove the cookies from the oven and immediately sprinkle flakey sea salt over the cookies.
Allow the cookies to cool for 10 minutes, then transfer the cookies to a wire baking rack, or eat immediately for warm, cookie goodness!
