How to cook
Grease or lay out baking paper in a 10″ (25 cm) square tray or 11″ (28 cm) in diameter round tray.
Preheat the oven to 360°F (180 °C). Beat the butter, sugar and vanilla until you get a fluffy mixture. Add the eggs one at a time, followed by the sifted flour and baking soda. Then mix them with the cocoa and milk, in which you've dissolved the vinegar or lemon juice beforehand.
Pour the mixture into the tray and put it to bake for about 1 hour and a little longer. Check if it is finally ready with a toothpick. Leave it for about 5 minutes in the tray before inverting the chocolate cake on a cooking grid to cool it completely.
If you wrap the layer in foil, you can store it in a cool place for up to 2 weeks. Before use, divide the layer into 2 -3 separate, thinner layers.