1. Separate the egg whites from the yolks. Beat the egg whites to hard snow with a pinch of salt - for best results you need to follow several tips: the container you'll be beating in needs to be perfectly dry, the mixer beaters too, there must not be a single drop of egg yolk on them, so clean them carefully. For the temperature of the egg whites - both cooled and ones at room temperature work excellent.
2. In a separate container, beat the yolks with the sugar and 1 tsp of lightly warmed water until whitened. Add the melted but not hot butter and while beating nonstop add the milk, cocoa, baking powder and flour (be sure to sift the dry ingredients). The mixture will become very runny and will spray while you're beating but don't let this bother you.
3. Add the fluffy egg whites slowly while swirling gradually until they become fully integrated, then pour the mixture into an oiled and floured tray. Bake in a preheated 320°F (160 °C) oven for 45 min.
4. After you take the ready cake out, leave it to cool. Once nearly cold, start making the chocolate topping. You can cut the cake into pieces for the topping to soak in better.
5. Heat the cream, sugar and butter on a moderate stove, add the truffles (set aside some for decoration) and the cut into pieces dark chocolate. Once they heat up, pour the hot topping over the cake and leave it to soak it in for at least 2-3 hours.
Notes: The cake turns out fantastic with a very gentle, melt-in-your-mouth texture due to the fact that there's very little flour in it. It's a cake that falls under the "impossible" category, where during baking 2 layers of different texture, type and color form, which is why I called it "magical".
If you don't want it too sweet, decrease the amount of sugar added.