Preheat oven to 350°F. Spray an 8 or 9-inch springform pan with nonstick cooking spray and set aside. Can also line an 8 or 9 inch cake baking pan lined with parchment paper or tin foil sprayed with non-stick cooking spray.
In a large mixing bowl, whisk together the flour, baking soda, and salt. Set aside.
Using a mixer, cream together the butter, brown sugar, and sugar until well combined for 1 -2 minutes. Add the egg, egg yolk, and vanilla extract and mix until fully combined.
Slowly mix in the dry ingredients and continue mixing until just combined, then mix in the chocolate chips.
Transfer the cookie dough into the prepared springform pan and spread it out into one even layer.
Bake at 350°F for 25 minutes for a 9" and 30 minutes for an 8" or until the top of the cookie cake is set and lightly browned.
Remove from the oven and allow to cool completely before removing from the pan.
Once cooled, decorate cake with frosting by piping frosting and and adding sprinkles for your special occasion.