Preheat an oven to 180c (350f) and prepare an 8-inch cake pan with parchment paper.
Into a large mixing bowl, add the softened butter, granulated sugar, brown sugar, vanilla extract, and kosher salt, and mix with an electric hand mixer until well combined and creamy.
Add the egg and egg yolk and mix until creamy and smooth.
Add the flour, and baking soda, and mix until almost combined.
Add the chocolate chips and chopped Oreos and mix until just combined. Do not overmix!
Transfer the mixture to the prepared cake pan and bake in a preheated 180c (350f) for 25-30 minutes. The cake should look done on the top (dry on the top and golden brown).
Let the cookie cake cool in room temperature for at least 2 hours. Remove from pan and pipe dollops of freshly made whipped cream or your favorite frosting around the edges of the cake. Serve and enjoy!
Notes
Use room temperature ingredients. It is important that you use room-temperature ingredients like eggs and butter. This step ensures that your mixture mixes into a homogenous mixture and bakes perfectly.
Don’t overmix the batter, you don’t want to develop the gluten in the flour. This step ensures you have moist cookies and not dense and dry cookies.
Make sure that your butter is at room temperature. An hour or two before making these cookies, take the butter out of the fridge and let it come to room temperature. The butter should be soft to the touch. If your butter is too cold, it will be harder to mix and there will be lumps of butter in the dough.
Measure your flour correctly! When measuring your flour, avoid scooping it with a measuring cup. Instead, stir the flour with a spoon to create as many air pockets as possible, and spoon it into your measuring cup. Finally, level it with a back of a knife.
Be patient! Let the cookie cake cool completly to room temperature for at least two hours before removing it from the pan.