Step 1

Prepare three 8 inch cake pans with parchment paper circles in the bottom, and grease the sides.

Step 2

Add all dry ingredients to a large bowl and whisk together.

Step 3

Add eggs, buttermilk and vegetable oil to the dry ingredients and mix well.

Step 4

Add vanilla to boiling water and add to mixture. Mix well.

Step 5

Divide batter between three cakes pans and bake at 300 degrees for about 30-33 minutes, or until a toothpick comes out with a few crumbs.

Step 6

Remove cakes from oven and allow to cool for about 10 minutes, then remove to cooling racks to cool completely.

Step 7

Make icing while cakes cool. Beat together butter and shortening until smooth.

Step 8

Slowly add 4 cups of powdered sugar and mix until smooth.

Step 9

Add vanilla and Oreo crumbs and mix until smooth.

Step 10

Add another 4-5 cups of powdered sugar and mix until smooth. Add water or milk until you get a smooth consistency.

Step 11

Set aside about 3 1/2 cups of icing for the filling inside the cake and add chopped Oreos, if using.

Step 12

Once cakes are cool, remove cake domes from top with a large serrated knife.

Step 13

Place first layer of cake on cake plate. Spread 1/2 of the icing with the chopped Oreos on top in an even layer.

Step 14

Add second layer of cake and add the rest of the of icing with chopped Oreos on top in an even layer.

Step 15

Add final layer of cake on top and frost the outside of the cake with remaining frosting. Feel free to use my tutorial for how to frost a smooth cake.

Step 16

To make the chocolate ganache, add the chocolate chips to a medium sized bowl (see my tips on making chocolate ganache).

Step 17

Heat the heavy whipping cream just until it begins to boil, then pour it over the chocolate chips. Allow it to sit for 2-3 minutes, then whisk until smooth.

Step 18

Drizzle the chocolate ganache around the edge of the cake, then pour the remainder of the ganache on top of the cake and spread evenly. I like to use a squeeze bottle for drizzling around the edges.

Step 19

Allow the ganache to firm up a bit, then pipe the remainder of the frosting around the top edge of the cake (see my tips on making a chocolate drip cake) and add an Oreo between each swirl. I used Ateco tip 847.

Step 20

Sprinkle a few Oreo crumbs onto to the cake, if desired, then serve. Cake is best when well covered for 3-4 days.