The first thing you are going to do is melt 8 oz (1 cup) of the chocolate with the butter in a small pot. I would suggest you do this on a medium / medium high heat. Stir to make sure that it does not burn and cake to the bottom.
Once your chocolate is melted and is beautiful, smooth, and has the prettiest shine, remove from the heat.
While it cools a bit, beat your eggs and sugar together for 5 minutes. It will be beautifully light and fluffy and almost a golden color. Once it is that perfect color and is combined, add your vanilla and beat for another minute.
You are now going to add your chocolate to your egg mixture. Allow it to combine for a few minutes.
While it is mixing, combine your flour, tapioca flour, and baking powder in one bowl and mix it together (with a fork or a whisk).
Add your flour mixture to your to your bowl and allow the batter to really come together.
Now, your batter should not be super runny. It should be like a brownie batter. If it is not, allow it to cool a bit, it is just that the chocolate was added when it was still a bit too warm.
You are now going to take the 4 oz (1/2 cup) of remaining chocolate chips and use a spatula to fold them into your cookie batter.
Set your oven to 350°F
Use an ice cream scoop to scoop out your batter onto cookie sheets.
Sprinkle them with kosher salt, and put in the oven.
Bake for 10-12 minutes and then remove from the oven. Allow them to sit on the pan for about 10 minutes. Then you can dig in!