Extra chocolate chips, white chocolate chips or M&M's for sprinkling on top
Instructions
Preheat the oven to 350 degrees F.
In a large microwave-safe bowl, combine the butter and chocolate chips. Microwave on 50% power for 1 minute. Stir and repeat 1-minute intervals until the chocolate and butter are melted and combined after stirring.
Stir in the granulated and brown sugars. Then whisk in the egg and vanilla.
In a separate medium bowl, whisk together the flour, cocoa, salt and soda. Stir the dry ingredients into the chocolate mixture until no dry streaks remain.
Line a large, rimmed baking sheet (11X17-inch) with parchment paper or foil (grease if using foil) and press the cookie into about a 10-inch circle. The dough may seem a bit soft but that's ok. I gather the dough into a ball with my hands, transfer it to the baking sheet and press into a circle. If the dough is too soft to work with, refrigerate for 20-30 minutes.
Top the cookie with chocolate chips or M&M's, pressing them lightly into the dough.
Bake for 13-14 minutes. Don't overbake or the cookie will be a bit dry! Let the cookie cool completely on the baking sheet so it won't break upon transferring.
Notes
Cake Circle: this baked cookie should fit just about right on one of those 12-inch cardboard cake circles if you want to transport it or give it away!