Using a serrated knife, slice the domes off the cakes, ensuring each is as flat as possible
Place one cake layer on a serving plate and generously spread a layer of frosting on the top. Gently place the next cake layer on the frosting making sure it is level. Repeat until all layers of the cake have been used up.
Spread a thin layer of icing on the sides and top of the cake and use a cake scraper to level it out.
If desired: Fill a piping bag with a small round nozzle with the chocolate ganache. Create a drip on the edges of the cake with the ganache. Use the remaining frosting to decorate the top of the cake. Top the cake with cookie crumbs and vegan chocolate.
Serve immediately or set aside in the fridge in a large airtight container until ready to serve! Store the cake in the fridge for up to 5 days or in the freezer for up to 1 month.