Step 1

Preheat oven to 350°F (180°C). Prepare a 9 inch cake pan with parchment paper in the bottom and baking spray on the sides. Set aside.

Step 2

Combine the flour, baking soda and salt in a medium sized bowl and set aside.

Step 3

Cream the butter and sugars together in a large mixer bowl on medium speed until light in color and fluffy, 2-3 minutes. You should be able to see the change in color and texture and know it’s ready.

Step 4

Add the egg and mix until well combined.

Step 5

Add the vanilla extract and mix until well combined.

Step 6

Add the dry ingredients to the butter mixture and mix until the dough is just well combined. Do not over mix. Once it’s well combined, use a rubber spatula to help it come together to form a more cohesive ball.

Step 7

Press the cookie dough evenly into the cake pan and bake for 15-20 minutes, or until the edges just begin to turn golden.

Step 8

Allow to cool completely in the pan. It will firm up as it cools.

Step 9

Once cool, quickly invert the cookie onto a cooling rack. Quickly place another cooling rack on the bottom of the cookie (which is now facing up) and invert again, so that the cookie cake is upright.

Step 10

To make the buttercream, add the butter to a large mixer bowl and beat until smooth.

Step 11

Add about half of the powdered sugar and mix until well combined and smooth.

Step 12

Add the vanilla extract and a tablespoon of cream or water and mix until well combined and smooth.

Step 13

Add the rest of the powdered sugar and mix until smooth. Add more cream or water to get the right consistency.

Step 14

Place the buttercream in a piping bag fitted with a piping tip (I used Ateco and pipe shells of frosting around the outer edge of the cake.