These are my tips: Make sure to line and grease the pan with tinfoil. The cake is super dense and sticky, and this is an essential if not irritating step.
Allow two days to make it, not because it’s hard, but because it needs time to set up properly. Allow it to cool before peeling away the tinfoil.
When it comes out of the oven it should be cracked and puffy. Level the top by pushing it down with a spatula before it cools completely. This way you can flip it for service and have a nice top by using the bottom as the top, and you don’t have to cut anything away by making it even.
For frosting we did one of two things. Either strain some heated raspberry jam and drizzle that on, or make a nice ganache and poor it on warm to coat the cake.
Or you can always use a doily and do a powdered sugar scrim.
Last and most important, be sure to use a high quality chocolate and good strong coffee.