In a medium bowl, whisk together the flour, baking soda, and salt. Set aside.
In a stand mixer fitted with a paddle attachment (or hand mixer) cream the butter, shortening, granulated and brown sugars, and vanilla on medium speed until creamy, about 3 minutes.
Add the eggs, one at a time, beating on medium speed until incorporated. Add the flour mixture all at once and mix until just incorporated. mix in the chopped chocolate pieces. You may need to give the bowl a couple of swipes with a rubber spatula at the end to make sure the chocolate is evenly distributed.
Line a baking sheet with parchment paper. Scoop the cookie dough using a 3 tablespoon scoop (I used the 1.5 tablespoon scoop, the recipe calls for a 3 tablespoon scoop) portion scoop onto baking sheet. You can make the cookies larger or smaller, but it will affect the bake time. For 1.5 tablespoon mine baked in 9-10 minutes.
Refrigerate the dough balls for at least 30 minutes; but if you have the time, they improve if you let them sit for 24 to 36 hours. There's never enough room in my fridge for a baking sheet, so I just refrigerate the dough in the bowl and then scoop them after.
After they are chilled, you can bake them or freeze the dough balls for baking later.
Pre heat the oven to 375. Line a baking sheet with parchment paper.
Evenly space six chilled cookie balls on the prepared sheet and sprinkle them with flakey sea salt. Bake in the middle of the oven for about 12 minutes or until golden brown and slightly puffed. Re[eat with as many batches as you need.
Allow the cookies to cool slightly on the baking sheet, until you can move them without them falling apart, about 5 minutes. Then move them to a cooling rack to finish cooling.