Step 1

Preheat oven to 350 degrees. Place parchment paper in the bottom of a 9 inch cake pan and grease the sides.

Step 2

Cream butter and sugars together until light and fluffy, about 3-4 minutes.

Step 3

Mix in egg and vanilla extract.

Step 4

Combine dry ingredients in a another bowl, then add them to the butter mixture and mix until well combined. Dough will be thick.

Step 5

Stir in chocolate chips.

Step 6

Press the dough evenly into the cake pan.

Step 7

Bake for 21-24 minutes or until the edges are slightly golden. The center will look undercooked, but it will continue cooking and firm up as it cools.

Step 8

Remove from oven and set aside to cool completely in the cake pan. It may still look a little undercooked until completely cool and firm. Once cooled, the center should be firm and it’ll be easier to remove it from the pan without it falling apart.

Step 9

Preheat oven to 350 degrees. Place parchment paper in the bottom of a 9 inch cake pan and grease the sides.

Step 10

To make the brownie, add the butter and chocolate to a heat-proof bowl (I use my mixer bowl) and set it over a pot of simmering water. Melt the butter and chocolate, stirring until smooth. Set aside to cool a bit.

Step 11

Whisk together the sugar, vanilla extract and eggs in a medium bowl until well combined.

Step 12

Combine the dry ingredients in another medium bowl.

Step 13

Whisk the cooled chocolate mixture into the egg mixture and combine.

Step 14

Gently stir the flour mixture into the chocolate mixture until well combined.

Step 15

Pour the batter evenly into the prepared pan and bake for 35-38 minutes, or until a toothpick inserted comes out with a few sticky crumbs. You don’t want to over bake it.

Step 16

Remove brownie from oven and set aside to cool completely in the pan, then remove from the pan.

Step 17

Preheat oven to 350 degrees. Place parchment paper in the bottom of a 9 inch cake pan and grease the sides.

Step 18

Whisk together flour, sugar baking powder and salt in a large mixing bowl.

Step 19

Whisk together egg whites, sour cream, milk and vanilla extract in a medium bowl, then add to the flour mixture and mix on medium speed just until smooth.

Step 20

Add melted butter and mix until combined.

Step 21

Stir in the Oreo crumbs and chopped Oreos.

Step 22

Pour batter evenly into prepared cake pan and bake for 34-36 minutes, or until a toothpick inserted in the center comes out with a few crumbs.

Step 23

Remove cake from oven and allow to cool for 2-3 minutes, then remove from pan to a cooling rack to finish cooling.

Step 24

Beat the butter and shortening together until smooth.

Step 25

Slowly add about half of the powdered sugar, mixing until smooth between each addition of powdered sugar.

Step 26

Add the vanilla extract, cocoa powder and 4 tablespoons of water or milk to the frosting and mix until smooth.

Step 27

Slowly add the remaining powdered sugar, mixing until smooth between each addition of powdered sugar.

Step 28

Add additional water to the frosting as needed to get a smooth consistency.

Step 29

Use a large serrated knife to remove the top edges from the cookie cake so that it’s flat and remove the dome from the top of the oreo cake. If the top of the brownie isn’t flat, trim it so that it is. See my tips on how to level a cake.

Step 30

Place the cookie cake on a serving plate or cardboard cake circle and top with about 1 cup of frosting. Smooth frosting into an even layer.

Step 31

Add about half of the additional crushed Oreos on top of the frosting and press into the frosting.

Step 32

Add the Oreo cake and top with about 1 cup of frosting. Smooth frosting into an even layer.

Step 33

Add remaining half of the additional crushed Oreos on top of the frosting and press into the frosting.

Step 34

Add the brownie to the top of the cake.

Step 35

Add a crumb coat and frost the outside of the cake. For help with getting a smooth cake, refer to my tutorial on how to frost a smooth cake with buttercream.

Step 36

Pipe swirls around the top edge of the cake. I use Ateco tip 844, but Wilton 2D or 1M would work as well.

Step 37

To make the chocolate ganache, add the additional chocolate chips to a heat proof bowl (see my tips on making chocolate ganache).

Step 38

Microwave the heavy whipping cream until boiling, then pour over the chocolate chips. Cover the bowl with clear wrap for about 5 minutes, then whisk until smooth.

Step 39

Use a spoon to drizzle the chocolate ganache down the sides of the cake. See my tips on making a chocolate drip cake.

Step 40

Pour remaining ganache onto the top of the cake and spread into an even layer in the middle of the piped swirls.

Step 41

Finish the cake off with chocolate chip cookies and Oreos that have been cut in half.