1
To make the buttermilk, add 1 large tablespoon of white alcoholic vinegar (the pickling kind) to one cup of milk. Stir well and leave for 5-10 minutes.
2
Take a round cake tin (26cm diameter), butter the inside of the tin and all around and line all sides, including the edge, with baking paper. Preheat the oven to 170 C.
3
Mix all the wet and dry ingredients together by hand in a large bowl: 375 g flour, 170 g cocoa powder, 1,5 teaspoons salt, 1 large spoonful of baking soda, 2 small teaspoons baking powder, 500 g sugar, 180 ml oil, 370 g buttermilk, 3 teaspoons vanilla extract, 3 large eggs ( whisk them a little separately beforehand).
4
Mix all the above ingredients together slowly with a whisk and add 370 ml of hot water to the mixture (to dissolve the cocoa powder, if you had put the water in earlier, on top of the eggs, it would have cooked ;) ).
5
The sponge cake batter comes out runny, you divide it into two or more parts - as you like and depending on the baking tray you have. I usually pour all the batter into the baking tray, bake it very slowly because the baking time increases, and when I see that it wants to burn a little on the top, but the batter is still runny inside, then I cover the cake with alufoli and put the tray back in the oven to finish baking. The cake is baked when the toothpick you stick in the middle comes out dry. If you think of cutting the cake into several layers, let it cool completely!
6
Also make a mixture to water the biscuit : 1 litre of water, a few tablespoons of icing sugar and a few tablespoons of rum... stir, taste, if it''s good for you, it''ll be good in the cake.
7
You make the custard when you have already cut the sponge and prepared the moistening mixture.
8
Chocolate cream: melt 400 g dark chocolate or edible chocolate with 1 tablespoon butter over a pan of steam, stir finely so there are no lumps, cool the chocolate slightly by dipping the bottom of the pan in cold water and stirring a little. If you were to stick your finger in the middle of the chocolate it should be nice and warm, not too hot. Then pour 600 ml of sweet whipping cream + 2 tablespoons of icing sugar into the mixer. Beat until almost whipped, then pour in the melted chocolate and add 10 ml of rum while mixing.
9
You can also mix hazelnuts, almonds, candied lemon or orange peel, sour cherries, practically anything into this cream. It''s a great cream and it can take anything.
10
To assemble the cake, you take a large tray or plate, something to serve the cake on. Take a clean rim from the baking tray you used to bake the sponge cake in. Place the first part of the sponge cake on the bottom, fasten the ring around it (even if there is a little air at the side, when the sponge cake is watered it will come apart). Soak the sponge cake with spoonfuls of sweet solution, when you press your fingers on the sponge cake it should be nice and wet and juicy. Then put a couple of spoonfuls of cream on the sponge, flatten it, sponge again, water, cream. Finally, just the sponge on top. Cover with cling film, place in the fridge, preferably overnight. The next day, decorate, you can even decorate with cream, put a host on top. You can also cover it with chocolate cream (make another 1x cream according to the recipe above) and decorate it like I did, with chocolate sticks and balls ... Or even cover it with buttercream and dress it in a cake mix, or sugar paste. As you wish.