Preheat oven to 325°F. Line a 9x9 baking pan with parchment paper, set aside.
For the brownies
Place butter, both cocoa powders and sugar in a large microwave-safe bowl and microwave for about 1 minute and 30 seconds, or until butter is melted. Whisk everything together until smooth. Stir in eggs and vanilla until combined. Pour in the flour and salt and mix until everything is completely combined. The batter will be very thick and glossy.
Pour the batter into your prepared baking pan and smooth it out until level. Bake for 22-25 minutes or until a toothpick comes out just slightly wet with a little bit of batter left on it - the top will not look so "wet" anymore when they are done. Underbaking the brownies just a bit is what makes them fudgy. Bake longer for less fudgy brownies.
For the truffle layer
In a large food processor, add Oreo cookies and pulse into a fine crumb. Dump in cream cheese and pulse until a "dough" like consistency forms and you can't see the cream cheese anymore.
Take pieces of the truffle mixture and pack it onto the warm brownies into an even layer while the brownies are still warm to the touch. The brownies need to be warm for the truffle layer to stick properly.
For the chocolate layer
In a small bowl, melt the chocolate chips and shortening at 30 second increments in the microwave until completely smooth and pourable. Pour the chocolate on top of the truffle layer and spread it out with a rubber spatula into a smooth and even layer.
Place tray back into the refrigerator for 15-20 minutes to allow the top to set up properly. Take the pan out and allow the brownies to warm up for a few minutes for smoother cutting lines.
Notes
Storage instructions: These bars will stay fresh for up to 5 days stored in an airtight container.