For the top, melt the chocolate together with the butter and sugar, on low heat then set aside.
In a bowl, sift the flour together with the cocoa and baking powder. Separately mix the eggs then add the oil, in a thin thread and finally the milk. Pour the composition over the flour and mix until smooth.
At the end add the melted chocolate and mix well. Divide the composition into three equal parts and bake three sheets in a round tray (24 cm) lined with baking paper.
Bake the sheets on the right heat, until they pass the toothpick test. After they are baked, let them cool on a kitchen grill, without overlapping them.
For the cream, put the chocolate on low heat together with the whipped cream. After it has melted, set it aside and mix until it is homogenous, then leave it to cool and put it in the fridge (preferably overnight). I was in a time crisis and I put the cream in the freezer for 20 minutes. After it has cooled, mix the cream well until it becomes frothy.
On a plate we place a sheet around which we mount the cake ring. Spread half of the chocolate cream over the sheet, cover with the second sheet and the rest of the cream. Cover with the last sheet of cake and refrigerate for 2 hours.
Meanwhile, prepare the cream for garnish. Sift the powdered sugar and mix it with cocoa. Add the melted butter and start mixing then add the milk. Mix for a few minutes, until the cream is homogeneous and the sugar is no longer felt. At the end add the vanilla extract and mix well.
Coat the tor with cream (for the top we use a very thin layer). We put the remaining cream in a posh with a star tip and form the roses (here you will find a video that will help you). I left the edges of the cake unfinished.
Put the cake in the fridge until ready to serve.