In a medium bowl, add the flour, cocoa powder, baking soda, baking powder, and cornstarch. Whisk together then set aside.
In a large mixing bowl, beat together the butter, granulated sugar, and brown sugar until light and fluffy (about 2 minutes on medium speed). Add vanilla extract and eggs and beat together until combined. Use a rubber spatula to scrape the sides of the mixing bowl.
Turn the mixer on low and and gradually add half of the dry ingredients to the butter mixture. Beat until combined. Add half of the heavy cream and mix to combine. Add in the remaining dry mixture and the remaining cream.
Beat in the chocolate chips just until combined.
Cover dough with plastic wrap and chill for 1 hour in the refrigerator.
Preheat the oven to 350 degrees and line baking sheets with parchment paper.
Use a cookie scoop to make balls from the chilled dough. Roll each ball between the palms of your hands for a smooth cookie. Space 2” apart on prepared cookie sheets.
Bake for 9 minutes and remove from the oven. Sprinkle several additional chocolate chips over the tops of the warm, baked cookies if desired.
Transfer cookies to a cooling rack and allow to cool.