In a medium bowl, whisk together the flour, baking soda, and salt. Set aside.

In a stand mixer fitted with the paddle attachment, 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 #20 (3-tablespoon) portion scoop onto the baking sheet. You can make the cookies larger or smaller, but it will affect the baking time.

Refrigerate the dough balls for at least 30 minutes; but for 24 to 36 hours. After they are chilled, you can bake them or freeze the dough balls for baking later.

Preheat the oven to 375°F / 190°C. Line a baking sheet with parchment paper.

Evenly space six chilled cookie balls on the prepared sheet and sprinkle them with flaky sea salt. Bake in the middle of the oven for about 12 minutes or until golden brown and slightly puffed. Repeat 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.

Baker's Note: You can replace butter and shortening to ½ cup / 110g bacon fat plus ½ cup unsalted butter and add ¼ cup bacon pieces when you add the chocolate.