Spray and Line a baking sheet/jellyroll sheet cake pan with parchment and spray again.
In food processor,
Crush 25 Oreo cookies
with 4 Tbl. melted butter and
1/2 tsp. salt
Press into bottom of sheet pan. (No baking necessary)
With mixer, combine the following:
1 box chocolate fudge cake mix (15-18 oz.)
1 cup flour
1 cup sugar
3/4 tsp. salt
2 Tbl. cocoa powder
1-1/3 cups water
2 Tbl. oil
1 tsp. vanilla
1 cup sour cream
4 eggs
Cool completely before adding ganache or frosting.
Ganache:
2/3 cup heavy cream
1 Tbl. butter
6 oz. (1 cup) semi-sweet chocolate chips
1 Tbl. corn syrup
Heat cream to boiling in microwave. Add chocolate chips, corn syrup, Pour/Spread over cooled cake. Freeze cake with ganache for easier cutting later.
Oreo-White Chocolate-Cream Cheese Buttercream:
Make white chocolate ganache first:
1/4 cup heavy cream, heated to boiling in microwave
Add 8 oz. white chocolate chips or melts and stir until smooth.
Allow to cool
In stand mixer, cream together for a few minutes:
3 cubes real butter
1/2 bar cream cheese
6 cups powdered sugar
Cooled white ganache mixture
1 tsp vanilla (regular or clear)
Allow to beat for several minutes until it is light and fluffy.
Mix in 6 crushed Oreos (fine sand texture)