In a large bowl, whisk together the flour, cocoa powder, baking powder, and salt. Set aside.
1 cup all-purpose flour, 1/4 cup cocoa powder, 1 teaspoon baking powder, 1/2 teaspoon table salt
In the bowl of a stand mixer or in a large bowl using a hand mixer, or in the bowl of a stand mixer using the paddle attachment, cream together the brown sugar, white sugar, and butter until light and fluffy, about 3 to 6 minutes.
1/4 cup granulated sugar, 3/4 cup brown sugar, 4 tablespoons unsalted butter
Mix in the eggs one at a time. Then add in the vanilla, scraping down the sides of the bowl in between each addition.
1 1/2 teaspoon vanilla extract, 2 eggs
Add the flour mixture. Turn the mixer on low and beat until it is just combined enough that the flour will not fly out of the bowl. Turn the mixer up all the way and mix for just a few more seconds until fully combined, being careful not to over-beat.
Mix in the melted and cooled chocolate. Then mix in the chocolate chunks. Let batter sit, covered, on the kitchen counter for 30 minutes. This will help it become more fudgy. (Read more about this step here: Letting Dough Rest) 1 1/2 cups semi sweet chocolate chips, 1 cup chocolate chunks
Preheat the oven to 350 degrees Fahrenheit. Line rimmed baking sheets with parchment paper. Using a 1 1/2 tablespoon cookie scoop, scoop the cookies and roll them into balls. Add extra chocolate chunks to the tops to have the cookies look like the cookies in the pictures. Place the cookies 2 inches apart and bake for 10 to 14 minutes, rotating the pans halfway through cooking. Remove from the oven and after 2 minutes, transfer to a cooling rack until fully cooled.