Preheat the oven to 350°F. Line a baking sheet with parchment paper.
To make the dough: In the bowl of a stand mixer fitted with the paddle attachment, add the butter, cane sugar, dark brown sugar, and vanilla extract and mix on low until combined and there are no chunks of butter. Add the eggs and mix just slightly, enough to break the yolks.
In a separate bowl, add the dry ingredients: flour, cocoa powder, baking powder, and sea salt, and whisk together. Add to the butter mixture and mix on low until a stiff dough forms.
Add the mini chocolate chips and mix to combine completely.
Using your hands form a large log out of the cookie dough and flatten slightly so it’s about 1-inch thick, it should be about 13 x 3 inches.
Bake for 40 to 45 minutes or until the middle looks set, but not completely done.
Remove from oven and let rest for 15 to 20 minutes. Slice into 12 pieces, separate them, and bake again for 20 to 25 minutes, until crispy. Sprinkle with flaky sea salt immediately after coming out of the oven. Allow to cool completely on the baking sheet.
Store in a cool dry place for up to 7 days.