Preheat the oven to 160 ° C. Grease and flour the bottom and sides of a springform pan (at least 24 cm in diameter) or line with baking paper.
Slowly heat 125 g each of milk chocolate and dark chocolate with the butter, coffee and water in a large bowl, stirring occasionally (preferably in a water bath). When the chocolate and butter have melted, let the mixture cool to room temperature.
Meanwhile, mix the flour, cocoa powder and baking powder together in a bowl. Add the sugar and stir in.
In another bowl, beat the eggs with oil, vanilla flavor and buttermilk. Pull the mixture into the flour. Add the chocolate mixture in three stages and stir in until a smooth batter is formed. Put the batter in the springform pan and bake for about 1 hour 15 minutes to 1 ½ hours. It is best to prick the middle of the cake with a knife and check whether the dough still sticks to it, crumbs are okay.
Let the cake cool down, take it out of the springform pan and turn it over (alternatively: cut off the crust at the top)
For the topping, melt the rest of the chocolate with the cream and crème fraîche mixture over low heat. Stir occasionally. Let the icing cool down a little and cover the cake with it (the icing is not a hard icing, but a slightly softer coating).
Originally, the cake is eaten slightly warmed (possibly with whipped cream). Careful, very, very powerful!
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