Preparation Steps

• Preheat oven to 350°F. Prepare a 9-inch cake pan with parchment paper and spray the sides with baking spray.
• In a medium bowl, whisk together flour, cornstarch, baking soda, and salt.
• In a large bowl, cream the butter, light brown sugar, and granulated sugar on medium speed until light and fluffy, about 2-3 minutes.
• Add the egg and vanilla extract to the creamed mixture and mix until fully combined.
• Gradually add the flour mixture to the butter mixture and mix until just combined. Use a rubber spatula to form a cohesive dough ball.
• Fold in the semi-sweet chocolate chips until evenly distributed.
• Press the cookie dough evenly into the prepared cake pan. Press a few extra chocolate chips on top if desired.
• Bake for 18-20 minutes or until edges are golden and cake is set.
• Remove from oven and cool completely in the pan before transferring to a serving plate.
• To make the chocolate buttercream, beat butter until smooth. Add half of the powdered sugar and beat until combined.
• Add cocoa powder, vanilla extract, and 1 tablespoon heavy cream. Beat until smooth and combined.
• Add remaining powdered sugar and beat until smooth. Add extra cream if needed for desired consistency.
• Pipe the buttercream around the outer edge of the cooled cookie cake using a piping bag fitted with tip Ateco 844 (or your choice).
• Store cookie cake in an airtight container at room temperature for up to 24 hours; after that, refrigerate. Best served at room temperature.