Preheat oven to 350°F. Line two rimmed baking sheets with parchment paper and set aside.
To melt the chocolate mixture: add chocolate and butter to a large, heatproof bowl and place over a pot of simmering water. The water should just touch the bottom of the bowl; you don't want to submerge the bottom of the bowl in simmering water.
Whisk the chocolate and butter together as it melts. Once melted, turn off the heat and place the bowl on a heatproof surface to cool slightly.
Meanwhile, in a stand mixer with a whisk attachment, or a large bowl using a hand mixer, beat together eggs, granulated sugar, and brown sugar for 5 minutes. I prefer to use a standmixer so I can set a timer and allow the mixer to keep whisking continuously while I move on to the next step.
While the eggs and sugars are mixing, grab another large bowl and whisk together the cake flour, cocoa powder, baking powder, and salt until well blended.
Once the sugars and eggs have been mixing for exactly five minutes, pour the melted chocolate mixture into the bowl with the eggs and sugars and mix for about a minute. Then slowly add the combined dry ingredients into the bowl and mix just until all ingredients are incorporated.
Using a medium ice cream scoop, scoop out the dough (it will be wet and gooey) to form cookies onto the lined baking sheets. Be sure to leave about 2 inches of space between each cookie, as the dough will spread during baking.
If desired, sprinkle a little sea salt on top of each cookie.
Bake at 350°F for 11-12 minutes, then remove and allow them to sit in the baking sheet for at least 15-20 minutes before eating. The center will be soft and fudgy.
Notes
Dairy-free options: use Enjoy Life Dark Chocolate Chips and Earth Balance vegan butter.Storage tips: Cookies are best eaten fresh, the day they are made, but will still retain a slightly chewy center for up to three days. Keep cookies in an airtight container at room temperature for up to one week.