Preheat oven to 350°F (180°C), or 160°C if using a fan oven. and prepare a 9-inch (approx 22 cm) springform pan by placing a round of parchment paper in the bottom.

In the bowl of a stand mixer, equipped with a paddle attachment, cream the butter and both sugars together until light and fluffy, about 2 minutes.

Add the egg and vanilla extract and mix until just combined. Scrape the sides and bottom of the bowl and mix additionally if needed.

Add the dry ingredients to the butter mixture and mix until just combined and there are no dry spots remaining.

Add in the chocolate chips last and mix just enough to combine throughout the dough.

Press the dough into the bottom of the prepared springform pan. (NOTE: I found the easiest way to do this was to use a clean hand that is gently sprayed with non-stick spray to press the dough down into the bottom of the pan.)

Bake for 20-25 minutes or until the edges are golden brown and set. Be careful not to overcook the cookie. Keep in mind it will continue cooking when you take it out of the oven just like a regular cookie.

Remove from the oven and allow the cookie to cool completely in the pan before trying to remove it.

Once it is cool, transfer to a serving plate if desired and prepare the frosting.

In the bowl of a stand mixer, equipped with a paddle attachment, cream the butter on med-high speed for 3-4 minutes until smooth and fluffy.

Add in the powdered sugar, cocoa powder, vanilla extract, and heavy whipping cream. Mix on low until everything is combined, then slowly increase the speed to high for 1-2 minutes. If needed, add additional heavy cream, one tbsp at a time, until you get the consistency you want.

Add the frosting into a piping bag fitted with a piping tip of your choice. Generously pipe swirls of frosting around the edges of the cookie cake. Top with sprinkles if desired.

Serve immediately or store in an airtight container for up to three days.