In a mixing bowl, add softened butter and both white and brown sugars. Beat together until all of the butter is mixed and there are no clumps remaining.
Using a sifter, sift cocoa powder and flour into the mixture. Add the remaining dry ingredients: salt, cornstarch, and baking powder to the batter.
Use a hand mixer to combine all ingredients. Note: batter will be sticky and thick. That’s ok!!
Using a greased cookie scooper (just spray the scoop with cooking spray), scoop cookies into balls and place on the cookie sheet.
Bake for 8-10 minutes or until the edges of the cookies are golden brown. Enjoy!