Place the first chocolate cake layer onto a cake stand or serving plate.
Spread an even layer (4-5 tablespoons) of chocolate ganache over the cake layer. Refrigerate for 5–10 minutes until the ganache is slightly set.
Top with 4-5 scoops of Oreo whipped cream cheese frosting and spread it evenly.
Repeat with the second cake layer, adding the chocolate ganache first, followed by the Oreo frosting.
Place the final cake layer on top. Apply a thin crumb coat of Oreo frosting over the entire cake and refrigerate for 30 minutes.
Cover the cake with the remaining Oreo whipped cream cheese frosting, smoothing the top and sides with an offset spatula or cake scraper.
Melt the chocolate ganache to a thick-pouring consistency. Pour the chocolate ganache over the top of the cake, gently spreading it to the edges so it drips down the sides.
Decorate with swirls of Oreo frosting, Oreos and chocolate shavings. Refrigerate for 1-2 hours before slicing.
Store the cake covered in the refrigerator for up to 5 days. For the best flavor and texture, let it sit at room temperature for 15–20 minutes before serving.