Preheat the oven to 356ºF.
In a bowl, sift the pastry flour, and mix in the cocoa powder, baking powder, salt and sugar.
Next, add the oil and mix. After the oil add the rest of the liquid ingredients: the coffee, milk, vanilla and eggs and beat well to combine all the ingredients.
Now, divide the mixture between two greased 20 centimeter cake tins. Bake each of the tins for 30 minutes.
Once our cakes are baked, it's time to prepare the cream and chocolate frosting. Melt the chocolate and cream together in a bain-marie.
In a bowl, mix the sour cream and vanilla and a pinch of salt. Remove the chocolate from the heat and add it to the sour cream mixture. Mix well. Cool for a few minutes.
Take the cakes out of the tins. Put one of them on a tray and spread some of the chocolate cream over the top. Now, put the other cake on top and spread the rest of the cream over the whole cake.
Cool and decorate with sweet toppings like truffles or caramel sauce.