Preheat oven to 350 degrees F. Lightly coat a cookie sheet with non-stick spray or line with a sheet of parchment paper.
In a medium bowl, whisk together the flour, cocoa powder, baking powder, and salt. Set aside.
1 cup all-purpose flour, ¼ cup unsweetened cocoa powder, 1 teaspoon baking powder, ¼ teaspoon kosher salt
Add the butter and chocolate chips to a small saucepan. Place over medium heat and stir frequently until completely melted. Set aside.
½ cup unsalted butter, ¾ cup semi-sweet chocolate chips
In a large bowl, using a hand mixer or stand mixer fitted with the paddle attachment, mix together the brown sugar, granulated sugar, eggs, and vanilla extract.
1/3 cup light brown sugar – packed, ½ cup granulated sugar, 2 large eggs, 1 teaspoon vanilla extract
Using a spatula, or spoon, fold in the melted chocolate. Add the flour mixture and continue stirring until completely combined.
Using a medium cookie scoop, place balls of cookie dough onto the prepared cookie sheet about 2 inches apart.
Bake for 10 minutes, until the top is set and starts to crack. (Don’t overbake or you will lose the fudgy inside).
Allow the cookies to cool for a few minutes on the sheet and then move the cookies to a rack until completely cooled.