Preheat your oven to 350°F (175°C) and grease a 9-inch round cake pan.
In a medium bowl, whisk together the all-purpose flour, baking soda, and salt.
In a large mixing bowl, combine melted butter with brown sugar and granulated sugar until smooth. Add eggs and vanilla extract, stirring until fully incorporated.
Gradually stir in dry ingredients until just combined. Gently fold in the semi-sweet chocolate chips.
Spread the dough evenly into the prepared pan and bake for about 20-25 minutes until edges are golden brown and center is set yet soft.
Allow the cookie cake to cool in the pan on a wire rack for about 15 minutes.
Beat softened butter in a large mixing bowl until smooth. Gradually add sifted powdered sugar, mixing until velvety. Add heavy cream, vanilla extract, and salt, mixing until combined.