Preheat the oven to 356°F (180 °C). Sift the flour into a large bowl and stir in both sugars, the cocoa, baking soda, baking powder and salt. In another bowl, beat the eggs, oil and yogurt and mix them well into the dry mixture. Finally, top up with the hot coffee and stir until everything becomes homogeneous.
The cake layer mixture needs to be runnier than usual, allowing for juicier and softer cake layers. Pour it into a cake form with 8″ (20 cm) high walls, greased and dusted with cocoa.
Put it in to bake for about 45 minutes and then check it with a toothpick. If you don't have a cake form with high walls, bake the mixture in 3 separate lots because it inflates and the cake layer rises quite high.
Cool the finished cake layer and cut it into 3 equal parts. For the cream, heat the cream in a water bath and add the crushed chocolate. Stir until homogeneous. Remove from heat and cool the mixture for a few minutes, while stirring it. Beat the egg yolks well in a water bath, but the container they are in must not touch the water directly, so they don't cook.
Then while stirring nonstop, add them to the chocolate mixture. Put it in the refrigerator until it hardens, about 1 hour. The final step is to carefully mix it with the beaten egg whites, adding them in batches. Put the cream for 40-50 minutes in the refrigerator once again.
With this cream, stick the cake layers together. Optionally you can sprinkle each with a little rum. Coat the entire cake thoroughly with cream. Spray rosettes on top if desired and decorate with strawberries or other fruit. Leave to sit for at least 2 hours before serving.