Step 1

Preheat the oven to 350 degrees Fahrenheit. Line the bottom of a 9-inch round springform pan with parchment paper that has been cut in a circle to fit. Spray the sides of the pan with non-stick cooking spray.

Step 2

Whisk the flour, cornstarch, baking soda, and salt together in a medium bowl until combined.

Step 3

In a separate large bowl, beat 3/4 cup room temperature butter until smooth using an electric mixer. Add the brown sugar and granulated white sugar and beat until light and fluffy, about 3 minutes.

Step 4

Beat in the eggs and 1 teaspoon vanilla extract. Gradually add the dry ingredients, beating over low speed, until just combined.

Step 5

Stir in the 2 cups of crushed Oreos then press the dough into the prepared pan. Press some crumbled Oreo bits on top. Bake for 20-25 minutes, or until the top is golden brown and the center is set.

Step 6

To make the Oreo buttercream frosting, beat 1 cup of room temperature butter in a large bowl with an electric mixer. Pour in the heavy cream and 1 teaspoon vanilla extract and beat again until smooth. Gradually add the powdered sugar, then stir in the Oreo crumbs.

Step 7

Let the cookie cake cool for at least 1 hour before spreading the buttercream on top or piping into a design. I used a Wilton 1M star piping tip to pipe the design onto the cake. Crumble 2-3 more Oreos around the top of the cake for garnish, if desired.