Before we begin, I'm begging you to take the optional advance prep or refrigerating the dough for 24 hours. It takes the flavor and texture over the top! You can chill your dough 1-3 days in advance. When ready to bake set the chilled dough out on the counter for an hour or so until soft enough to tear off chunks to press into the pizza pan.
LET'S MAKE A COOKIE CAKE!
First bring butter and eggs to room temp. Butter is ready when a light imprint can be left in the stick of butter with your thumb. To soften faster, slice into chunks.
Measure flour by weight (best results) or using the fluff-spoon-level technique.
In a medium-large bowl, whisk together flour, cornstarch, baking soda, and salt. Set aside.
Cream together softened butter and both sugars in a stand mixer with the paddle attachment. Start at the lowest speed and increase as needed for approx. 2 minutes. A large bowl with an electric hand mixer may be used if needed.
Add in the egg and vanilla and continue to beat with the mixer to incorporate into the dough, approx. 30-45 seconds
Add flour mixture to the larger bowl slowly while you continue to beat on low speed. Once the flour is almost incorporated add chocolate chips and beat on low until the flour is fully incorporated. (take care not to over-mix at this point)
Place dough on a large sheet of plastic wrap and wrap securely. Refrigerate overnight or 1-3 days for advance prep.
READY TO BAKE?
Grab the dough from the fridge and allow to soften on the counter for one hour.
Preheat oven to 350°F and lightly grease the pizza pan with butter or line with parchment paper.
Break off chunks of dough and arrange on pizza pan. Press together to create an even layer of cookie dough in the pan, nearly all the way to the edges. Press some extra chocolate chips into the top of the dough before baking.
Bake in the pan on the center rack of the oven at 350°F for 16 minutes.
After 16 minutes, remove from oven and allow cookie cake to cool in the pan elevated on a wire cooling rack. It should be set and cool enough to frost after one hour. While it cools, make your frosting and plan for the fun part – the decorating!
COOKIE CAKE FROSTING
In the bowl of a stand mixer fitted with the paddle attachment or in a large mixing bowl using a handheld mixer, beat the butter until smooth and creamy, stopping to scrape down sides as needed. (approx. 1-2 minutes)
Add the powdered sugar and mix on low speed at first to incorporate then increase to medium speed and continue mixing for 1-2 minutes or until fully combined. Add the heavy cream, vanilla extract, and salt and continue mixing on medium speed until everything is well-combined, smooth, and easy to pipe.
Divide frosting into 2-3 bowls and use a small amount of gel food coloring to dye each a different color. Start with a drop or two, mix well, then add more as desired.
Transfer to piping bags with corresponding tips: I used Wilton open star tip 4B for the starburst accents and to pipe the circumference of the cake. To make the icing roses I used Wilton drop flower tip 2D. You could also use a 1M open star tip to create flowers. There are a few different tips you can use to make leaves. I used wilton tip #366.
After frosting, add your favorite festive sprinkles (totally optional) and enjoy!
Notes
Frosting can be made in advance and stored in the fridge just like the cookie dough. Bring back to room temp before frosting your cookie cake.If using a stainless steel or aluminum pizza pan (anything that isn't non-stick) simply line the bottom with parchment before adding the dough.Nutrition Facts below are estimated for cookie cake with frosting using an online recipe nutrition calculator. Adjust as needed based on slice size chosen and any adjustments made. Freel free to make more than 18 slices out of this giant cookie cake. Enjoy!