Preheat oven to 375 degrees (F). Bake time: 12 – 15 minutes.
Line 2 cookie sheet pans with parchment paper.
In a small bowl, mix your flour, baking soda, and salt, set aside.
In your stand mixer, combine butter with shortening until creamy.
Add in the sugars (white and brown) and cream on a low speed. Do not over-beat.
Add in vanilla and cream until just incorporated.
Then add in room temperature eggs to the butter and sugar mixture. Once incorporated, scrap the bowl.
Now add in the dry ingredients... flour, baking soda, and kosher salt and mix but do not over mix.
Finally, add in the chopped bittersweet chocolate just until incorporated.
Using a medium sized cookie scoop (1.5 - 2” diameter), scoop cookie dough, one cookie at a time into round balls and place on one of the parchment lined cookie sheet pans. Scoop until you have made all the cookies. Place these cookies into the refrigerator so the flavors can marry.
Place five of those cookies onto the second parchment lined pan and place into the oven. After the cookies have been in the oven for 9 minutes, using oven mitts grab one or both sides of the pan and lift and give it a solid bang.
Close the oven and finish baking the cookies. Time remaining should be 3 – 4 minutes, depending on your oven.
Remove from oven, let cool on the pan for a few minutes, sprinkle with flaky sea salt, and then remove cookies and place on a cooling rack.
Remove five more cookies from the refrigerator and bake accordingly until all cookies are baked.