Preheat oven to 350°F (175°C). Grease a 9-inch round cake pan or springform pan.
In a large bowl, cream the softened butter with brown and white sugars until light and fluffy.
Add eggs and vanilla extract to the butter mixture, mixing until well combined.
In a separate bowl, whisk together flour, baking soda, and salt.
Gradually add the dry ingredients to the wet mixture, mixing until just combined. Do not overmix.
Fold in chocolate chips gently.
Spread the dough evenly into the prepared pan, using a spatula to smooth the surface.
Bake for 20-25 minutes or until the edges are golden brown, and a toothpick comes out with a few moist crumbs.
Allow the cookie cake to cool completely in the pan before decorating or serving.